tests/test_json_backend.py

+# -*- coding: utf-8 -*-
+#
+# Copyright © 2019 Stephan Seitz <stephan.seitz@fau.de>
+#
+# Distributed under terms of the GPLv3 license.
+
+"""
+
+"""
+
+import sympy
+
+import pystencils
+from pystencils.backends.json import print_json, print_yaml, write_json, write_yaml
+import tempfile
+
+
+def test_json_backend():
+
+    z, y, x = pystencils.fields("z, y, x: [20,40]")
+    a = sympy.Symbol('a')
+
+    assignments = pystencils.AssignmentCollection({
+        z[0, 0]: x[0, 0] * a * x[0, 0] * y[0, 0]
+    })
+
+    ast = pystencils.create_kernel(assignments)
+
+    pj = print_json(ast)
+    # print(pj)
+    py = print_yaml(ast)
+    # print(py)
+
+    temp_dir = tempfile.TemporaryDirectory()
+    write_json(temp_dir.name + '/test.json', ast)
+    write_yaml(temp_dir.name + '/test.yaml', ast)

tests/test_json_serializer.py

+"""
+Test the pystencils-specific JSON encoder and serializer as used in the Database class.
+"""
+
+import numpy as np
+import tempfile
+
+from pystencils.config import CreateKernelConfig
+from pystencils import Target, Field
+from pystencils.runhelper.db import Database, PystencilsJsonSerializer
+
+
+def test_json_serializer():
+
+    dtype = np.float32
+
+    index_arr = np.zeros((3,), dtype=dtype)
+    indexed_field = Field.create_from_numpy_array('index', index_arr)
+
+    # create pystencils config
+    config = CreateKernelConfig(target=Target.CPU, function_name='dummy_config', data_type=dtype,
+                                index_fields=[indexed_field])
+
+    # create dummy database
+    temp_dir = tempfile.TemporaryDirectory()
+    db = Database(file=temp_dir.name, serializer_info=('pystencils_serializer', PystencilsJsonSerializer))
+
+    db.save(params={'config': config}, result={'test': 'dummy'})

tests/test_jupyter_extensions.ipynb

+%% Cell type:code id: tags:
+
+``` python
+from pystencils.session import *
+```
+
+%% Cell type:code id: tags:
+
+``` python
+dh = ps.create_data_handling(domain_size=(256, 256), periodicity=True)
+c_field = dh.add_array('c')
+dh.fill("c", 0.0, ghost_layers=True)
+```
+
+%% Cell type:code id: tags:
+
+``` python
+for x in range(129):
+    for y in range(258):
+        dh.cpu_arrays['c'][x, y] = 1.0
+```
+
+%% Cell type:code id: tags:
+
+``` python
+plt.scalar_field(dh.cpu_arrays["c"])
+```
+
+%% Output
+
+    <matplotlib.image.AxesImage at 0x117081c10>
+
+
+
+%% Cell type:code id: tags:
+
+``` python
+ur = ps.Assignment(c_field[0, 0], c_field[1, 0])
+config = ps.CreateKernelConfig(target=dh.default_target, cpu_openmp=False, skip_independence_check=True)
+ast = ps.create_kernel(ur, config=config)
+kernel = ast.compile()
+```
+
+%% Cell type:code id: tags:
+
+``` python
+c_sync = dh.synchronization_function_cpu(['c'])
+```
+
+%% Cell type:code id: tags:
+
+``` python
+def timeloop(steps=10):
+    for i in range(steps):
+        c_sync()
+        dh.run_kernel(kernel)
+    return dh.gather_array('c')
+```
+
+%% Cell type:code id: tags:
+
+``` python
+ps.jupyter.set_display_mode('video')
+```
+
+%% Cell type:code id: tags:
+
+``` python
+ani = ps.plot.scalar_field_animation(timeloop, rescale=True, frames=12)
+ps.jupyter.display_animation(ani)
+```
+
+%% Output
+
+    <IPython.core.display.HTML object>
+
+%% Cell type:code id: tags:
+
+``` python
+ps.jupyter.set_display_mode('image_update')
+```
+
+%% Cell type:code id: tags:
+
+``` python
+ani = ps.plot.scalar_field_animation(timeloop, rescale=True, frames=12)
+ps.jupyter.display_animation(ani)
+```
+
+%% Output
+
+
+
+%% Cell type:code id: tags:
+
+``` python
+def grid_update_function(image):
+    for i in range(40):
+        c_sync()
+        dh.run_kernel(kernel)
+    return dh.gather_array('c')
+```
+
+%% Cell type:code id: tags:
+
+``` python
+animation = ps.jupyter.make_imshow_animation(dh.cpu_arrays["c"], grid_update_function, frames=300)
+```
+
+%% Output
+
+
+
+%% Cell type:code id: tags:
+
+``` python
+ps.jupyter.set_display_mode("video")
+ps.jupyter.set_display_mode("window")
+ps.jupyter.set_display_mode("image_update")
+ps.jupyter.activate_ipython()
+```
+
+%% Output
+
+    ---------------------------------------------------------------------------
+    ImportError                               Traceback (most recent call last)
+Cell     In[14], line 2
+          1 ps.jupyter.set_display_mode("video")
+    ----> 2 ps.jupyter.set_display_mode("window")
+          3 ps.jupyter.set_display_mode("image_update")
+          4 ps.jupyter.activate_ipython()
+File     ~/pystencils/pystencils/src/pystencils/jupyter.py:115, in set_display_mode(mode)
+        113     display_animation_func = display_as_html_video
+        114 elif animation_display_mode == 'window':
+    --> 115     ipython.magic("matplotlib qt")
+        116     display_animation_func = display_in_extra_window
+        117 elif animation_display_mode == 'image_update':
+File     /opt/local/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/IPython/core/interactiveshell.py:2539, in InteractiveShell.magic(self, arg_s)
+       2537 magic_name, _, magic_arg_s = arg_s.partition(' ')
+       2538 magic_name = magic_name.lstrip(prefilter.ESC_MAGIC)
+    -> 2539 return self.run_line_magic(magic_name, magic_arg_s, _stack_depth=2)
+File     /opt/local/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/IPython/core/interactiveshell.py:2417, in InteractiveShell.run_line_magic(self, magic_name, line, _stack_depth)
+       2415     kwargs['local_ns'] = self.get_local_scope(stack_depth)
+       2416 with self.builtin_trap:
+    -> 2417     result = fn(*args, **kwargs)
+       2419 # The code below prevents the output from being displayed
+       2420 # when using magics with decodator @output_can_be_silenced
+       2421 # when the last Python token in the expression is a ';'.
+       2422 if getattr(fn, magic.MAGIC_OUTPUT_CAN_BE_SILENCED, False):
+File     /opt/local/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/IPython/core/magics/pylab.py:99, in PylabMagics.matplotlib(self, line)
+         97     print("Available matplotlib backends: %s" % backends_list)
+         98 else:
+    ---> 99     gui, backend = self.shell.enable_matplotlib(args.gui.lower() if isinstance(args.gui, str) else args.gui)
+        100     self._show_matplotlib_backend(args.gui, backend)
+File     /opt/local/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/IPython/core/interactiveshell.py:3603, in InteractiveShell.enable_matplotlib(self, gui)
+       3599         print('Warning: Cannot change to a different GUI toolkit: %s.'
+       3600                 ' Using %s instead.' % (gui, self.pylab_gui_select))
+       3601         gui, backend = pt.find_gui_and_backend(self.pylab_gui_select)
+    -> 3603 pt.activate_matplotlib(backend)
+       3604 configure_inline_support(self, backend)
+       3606 # Now we must activate the gui pylab wants to use, and fix %run to take
+       3607 # plot updates into account
+File     /opt/local/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/IPython/core/pylabtools.py:360, in activate_matplotlib(backend)
+        355 # Due to circular imports, pyplot may be only partially initialised
+        356 # when this function runs.
+        357 # So avoid needing matplotlib attribute-lookup to access pyplot.
+        358 from matplotlib import pyplot as plt
+    --> 360 plt.switch_backend(backend)
+        362 plt.show._needmain = False
+        363 # We need to detect at runtime whether show() is called by the user.
+        364 # For this, we wrap it into a decorator which adds a 'called' flag.
+File     /opt/local/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/matplotlib/pyplot.py:271, in switch_backend(newbackend)
+        268 # have to escape the switch on access logic
+        269 old_backend = dict.__getitem__(rcParams, 'backend')
+    --> 271 backend_mod = importlib.import_module(
+        272     cbook._backend_module_name(newbackend))
+        274 required_framework = _get_required_interactive_framework(backend_mod)
+        275 if required_framework is not None:
+File     /opt/local/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/importlib/__init__.py:126, in import_module(name, package)
+        124             break
+        125         level += 1
+    --> 126 return _bootstrap._gcd_import(name[level:], package, level)
+File     <frozen importlib._bootstrap>:1204, in _gcd_import(name, package, level)
+File     <frozen importlib._bootstrap>:1176, in _find_and_load(name, import_)
+File     <frozen importlib._bootstrap>:1147, in _find_and_load_unlocked(name, import_)
+File     <frozen importlib._bootstrap>:690, in _load_unlocked(spec)
+File     <frozen importlib._bootstrap_external>:940, in exec_module(self, module)
+File     <frozen importlib._bootstrap>:241, in _call_with_frames_removed(f, *args, **kwds)
+File     /opt/local/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/matplotlib/backends/backend_qt5agg.py:7
+          4 from .. import backends
+          6 backends._QT_FORCE_QT5_BINDING = True
+    ----> 7 from .backend_qtagg import (    # noqa: F401, E402 # pylint: disable=W0611
+          8     _BackendQTAgg, FigureCanvasQTAgg, FigureManagerQT, NavigationToolbar2QT,
+          9     FigureCanvasAgg, FigureCanvasQT)
+         12 @_BackendQTAgg.export
+         13 class _BackendQT5Agg(_BackendQTAgg):
+         14     pass
+File     /opt/local/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/matplotlib/backends/backend_qtagg.py:9
+          5 import ctypes
+          7 from matplotlib.transforms import Bbox
+    ----> 9 from .qt_compat import QT_API, _enum
+         10 from .backend_agg import FigureCanvasAgg
+         11 from .backend_qt import QtCore, QtGui, _BackendQT, FigureCanvasQT
+File     /opt/local/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/matplotlib/backends/qt_compat.py:135
+        133         break
+        134     else:
+    --> 135         raise ImportError(
+        136             "Failed to import any of the following Qt binding modules: {}"
+        137             .format(", ".join(_ETS.values())))
+        138 else:  # We should not get there.
+        139     raise AssertionError(f"Unexpected QT_API: {QT_API}")
+    ImportError: Failed to import any of the following Qt binding modules: PyQt6, PySide6, PyQt5, PySide2

tests/test_logarithm.py

+import pytest
+import numpy as np
+import sympy as sp
+
+import pystencils as ps
+
+
+@pytest.mark.parametrize('dtype', ["float64", "float32"])
+def test_log(dtype):
+    a = sp.Symbol("a")
+    x = ps.fields(f'x: {dtype}[1d]')
+
+    assignments = ps.AssignmentCollection({x.center(): sp.log(a)})
+
+    ast = ps.create_kernel(assignments)
+    code = ps.get_code_str(ast)
+    kernel = ast.compile()
+
+    # ps.show_code(ast)
+
+    if dtype == "float64":
+        assert "float" not in code
+
+    array = np.zeros((10,), dtype=dtype)
+    kernel(x=array, a=100)
+    assert np.allclose(array, 4.60517019)

pystencils_tests/test_loop_cutting.py → tests/test_loop_cutting.py

-import sympy as sp
 import numpy as np
+import sympy as sp
+
+import pytest
+
 import pystencils as ps
-from pystencils import Field
-from pystencils.cpu import create_kernel, make_python_function
+import pystencils.astnodes as ast
+from pystencils.field import Field, FieldType
 from pystencils.astnodes import Conditional, LoopOverCoordinate, SympyAssignment
+from pystencils.cpu import create_kernel, make_python_function
 from pystencils.kernelcreation import create_staggered_kernel
-from pystencils.transformations import move_constants_before_loop
-import pystencils.astnodes as ast
-from pystencils.transformations import simplify_conditionals, cleanup_blocks, cut_loop
+from pystencils.transformations import (
+    cleanup_blocks, cut_loop, move_constants_before_loop, simplify_conditionals)
 
 
 def offsets_in_plane(normal_plane, offset_int, dimension):
@@ -33,9 +36,9 @@ def test_staggered_iteration():
     s_arr_ref = s_arr.copy()
 
     fields_fixed = (Field.create_from_numpy_array('f', f_arr),
-                    Field.create_from_numpy_array('s', s_arr, index_dimensions=1))
+                    Field.create_from_numpy_array('s', s_arr, index_dimensions=1, field_type=FieldType.STAGGERED))
     fields_var = (Field.create_generic('f', 2),
-                  Field.create_generic('s', 2, index_dimensions=1))
+                  Field.create_generic('s', 2, index_dimensions=1, index_shape=(dim,), field_type=FieldType.STAGGERED))
 
     for f, s in [fields_var, fields_fixed]:
         # --- Manual
@@ -47,14 +50,18 @@ def test_staggered_iteration():
                                  sum(f[o] for o in offsets_in_plane(d, -1, dim)))
             cond = sp.And(*[conditions[i] for i in range(dim) if d != i])
             eqs.append(Conditional(cond, eq))
-        func = create_kernel(eqs, ghost_layers=[(1, 0), (1, 0), (1, 0)]).compile()
+        # TODO: correct type hint
+        config = ps.CreateKernelConfig(target=ps.Target.CPU, ghost_layers=[(1, 0), (1, 0), (1, 0)])
+        func = ps.create_kernel(eqs, config=config).compile()
 
         # --- Built-in optimized
         expressions = []
         for d in range(dim):
             expressions.append(sum(f[o] for o in offsets_in_plane(d, 0, dim)) -
                                sum(f[o] for o in offsets_in_plane(d, -1, dim)))
-        func_optimized = create_staggered_kernel(s, expressions).compile()
+        assignments = [ps.Assignment(s.staggered_access(d), expressions[i]) for i, d in enumerate(s.staggered_stencil)]
+        func_optimized = create_staggered_kernel(assignments).compile()
+        pytest.importorskip('islpy')
         assert not func_optimized.ast.atoms(Conditional), "Loop cutting optimization did not work"
 
         func(f=f_arr, s=s_arr_ref)
@@ -69,12 +76,13 @@ def test_staggered_iteration_manual():
     s_arr_ref = s_arr.copy()
 
     f = Field.create_from_numpy_array('f', f_arr)
-    s = Field.create_from_numpy_array('s', s_arr, index_dimensions=1)
+    s = Field.create_from_numpy_array('s', s_arr, index_dimensions=1, field_type=FieldType.STAGGERED)
 
     eqs = []
 
     counters = [LoopOverCoordinate.get_loop_counter_symbol(i) for i in range(dim)]
     conditions = [counters[i] < f.shape[i] - 1 for i in range(dim)]
+    conditions2 = counters[0] > f.shape[0] + 5
 
     for d in range(dim):
         eq = SympyAssignment(s(d), sum(f[o] for o in offsets_in_plane(d, 0, dim)) -
@@ -82,7 +90,13 @@ def test_staggered_iteration_manual():
         cond = sp.And(*[conditions[i] for i in range(dim) if d != i])
         eqs.append(Conditional(cond, eq))
 
-    kernel_ast = create_kernel(eqs, ghost_layers=[(1, 0), (1, 0), (1, 0)])
+    # this conditional should vanish entirely because it is never true
+    eq = SympyAssignment(s(0), f[0, 0])
+    cond = sp.And(*[conditions2])
+    eqs.append(Conditional(cond, eq))
+
+    config = ps.CreateKernelConfig(target=ps.Target.CPU, ghost_layers=[(1, 0), (1, 0), (1, 0)])
+    kernel_ast = ps.create_kernel(eqs, config=config)
 
     func = make_python_function(kernel_ast)
     func(f=f_arr, s=s_arr_ref)
@@ -97,6 +111,7 @@ def test_staggered_iteration_manual():
     move_constants_before_loop(kernel_ast.body)
     cleanup_blocks(kernel_ast.body)
 
+    pytest.importorskip('islpy')
     assert not kernel_ast.atoms(Conditional), "Loop cutting optimization did not work"
 
     func_optimized = make_python_function(kernel_ast)
@@ -106,11 +121,14 @@ def test_staggered_iteration_manual():
 
 def test_staggered_gpu():
     dim = 2
-    f, s = ps.fields("f, s({dim}): double[{dim}D]".format(dim=dim))
+    f = ps.fields(f"f: double[{dim}D]")
+    s = ps.fields("s({dim}): double[{dim}D]".format(dim=dim), field_type=FieldType.STAGGERED)
     expressions = [(f[0, 0] + f[-1, 0]) / 2,
                    (f[0, 0] + f[0, -1]) / 2]
-    kernel_ast = ps.create_staggered_kernel(s, expressions, target='gpu', gpu_exclusive_conditions=True)
+    assignments = [ps.Assignment(s.staggered_access(d), expressions[i]) for i, d in enumerate(s.staggered_stencil)]
+    kernel_ast = ps.create_staggered_kernel(assignments, target=ps.Target.GPU, gpu_exclusive_conditions=True)
     assert len(kernel_ast.atoms(Conditional)) == 4
 
-    kernel_ast = ps.create_staggered_kernel(s, expressions, target='gpu', gpu_exclusive_conditions=False)
+    assignments = [ps.Assignment(s.staggered_access(d), expressions[i]) for i, d in enumerate(s.staggered_stencil)]
+    kernel_ast = ps.create_staggered_kernel(assignments, target=ps.Target.GPU, gpu_exclusive_conditions=False)
     assert len(kernel_ast.atoms(Conditional)) == 3

tests/test_match_subs_for_assignment_collection.py

+# -*- coding: utf-8 -*-
+#
+# Copyright © 2019 Stephan Seitz <stephan.seitz@fau.de>
+#
+# Distributed under terms of the GPLv3 license.
+
+"""
+
+"""
+
+import sympy as sp
+
+import pystencils
+from pystencils.typing import TypedSymbol, BasicType
+
+
+def test_wild_typed_symbol():
+    x = pystencils.fields('x:  float32[3d]')
+    typed_symbol = TypedSymbol('a', BasicType('float64'))
+
+    assert x.center().match(sp.Wild('w1'))
+    assert typed_symbol.match(sp.Wild('w1'))
+
+    wild_ceiling = sp.ceiling(sp.Wild('w1'))
+    assert sp.ceiling(x.center()).match(wild_ceiling)
+    assert sp.ceiling(typed_symbol).match(wild_ceiling)
+
+
+def test_replace_and_subs_for_assignment_collection():
+
+    x, y = pystencils.fields('x, y:  float32[3d]')
+    a, b, c, d = sp.symbols('a, b, c, d')
+
+    assignments = pystencils.AssignmentCollection({
+        a: sp.floor(1),
+        b: 2,
+        c: a + c,
+        y.center(): sp.ceiling(x.center()) + sp.floor(x.center())
+    })
+
+    expected_assignments = pystencils.AssignmentCollection({
+        a: sp.floor(3),
+        b: 2,
+        c: a + c,
+        y.center(): sp.ceiling(x.center()) + sp.floor(x.center())
+    })
+
+    assert expected_assignments == assignments.replace(1, 3)
+    assert expected_assignments == assignments.subs({1: 3})
+
+    expected_assignments = pystencils.AssignmentCollection({
+        d: sp.floor(1),
+        b: 2,
+        c: d + c,
+        y.center(): sp.ceiling(x.center()) + sp.floor(x.center())
+    })
+
+    print(expected_assignments)
+    print(assignments.subs(a, d))
+    assert expected_assignments == assignments.subs(a, d)
+
+
+def test_match_for_assignment_collection():
+
+    x, y = pystencils.fields('x, y:  float32[3d]')
+    a, b, c, d = sp.symbols('a, b, c, d')
+
+    assignments = pystencils.AssignmentCollection({
+        a: sp.floor(1),
+        b: 2,
+        c: a + c,
+        y.center(): sp.ceiling(x.center()) + sp.floor(x.center())
+    })
+
+    w1 = sp.Wild('w1')
+    w2 = sp.Wild('w2')
+    w3 = sp.Wild('w3')
+
+    wild_ceiling = sp.ceiling(w1)
+    wild_addition = w1 + w2
+
+    assert assignments.match(pystencils.Assignment(w3, wild_ceiling + w2))[w1] == x.center()
+    assert assignments.match(pystencils.Assignment(w3, wild_ceiling + w2)) == {
+        w3: y.center(),
+        w2: sp.floor(x.center()),
+        w1: x.center()
+    }
+    assert assignments.find(wild_ceiling) == {sp.ceiling(x.center())}
+    assert len([a for a in assignments.find(wild_addition) if isinstance(a, sp.Add)]) == 2

tests/test_math_functions.py

+import pytest
+import sympy as sp
+import numpy as np
+import pystencils as ps
+from pystencils.fast_approximation import fast_division
+
+
+@pytest.mark.parametrize('dtype', ["float64", "float32"])
+@pytest.mark.parametrize('func', [sp.Pow, sp.atan2])
+@pytest.mark.parametrize('target', [ps.Target.CPU, ps.Target.GPU])
+def test_two_arguments(dtype, func, target):
+    if target == ps.Target.GPU:
+        pytest.importorskip("cupy")
+    dh = ps.create_data_handling(domain_size=(10, 10), periodicity=True, default_target=target)
+
+    x = dh.add_array('x', values_per_cell=1, dtype=dtype)
+    dh.fill("x", 0.0, ghost_layers=True)
+    y = dh.add_array('y', values_per_cell=1, dtype=dtype)
+    dh.fill("y", 1.0, ghost_layers=True)
+    z = dh.add_array('z', values_per_cell=1, dtype=dtype)
+    dh.fill("z", 2.0, ghost_layers=True)
+
+    config = ps.CreateKernelConfig(target=target)
+
+    # test sp.Max with one argument
+    up = ps.Assignment(x.center, func(y.center, z.center))
+    ast = ps.create_kernel(up, config=config)
+    code = ps.get_code_str(ast)
+    if dtype == 'float32':
+        assert func.__name__.lower() in code
+    kernel = ast.compile()
+
+    dh.all_to_gpu()
+    dh.run_kernel(kernel)
+    dh.all_to_cpu()
+
+    np.testing.assert_allclose(dh.gather_array("x")[0, 0], float(func(1.0, 2.0).evalf()),
+                               13 if dtype == 'float64' else 5)
+
+
+@pytest.mark.parametrize('dtype', ["float64", "float32"])
+@pytest.mark.parametrize('func', [sp.sin, sp.cos, sp.sinh, sp.cosh, sp.atan, sp.floor, sp.ceiling])
+@pytest.mark.parametrize('target', [ps.Target.CPU, ps.Target.GPU])
+def test_single_arguments(dtype, func, target):
+    if target == ps.Target.GPU:
+        pytest.importorskip("cupy")
+    dh = ps.create_data_handling(domain_size=(10, 10), periodicity=True, default_target=target)
+
+    x = dh.add_array('x', values_per_cell=1, dtype=dtype)
+    dh.fill("x", 0.0, ghost_layers=True)
+    y = dh.add_array('y', values_per_cell=1, dtype=dtype)
+    dh.fill("y", 1.0, ghost_layers=True)
+
+    config = ps.CreateKernelConfig(target=target)
+
+    # test sp.Max with one argument
+    up = ps.Assignment(x.center, func(y.center))
+    ast = ps.create_kernel(up, config=config)
+    code = ps.get_code_str(ast)
+    if dtype == 'float32':
+        func_name = func.__name__.lower() if func is not sp.ceiling else "ceil"
+        assert func_name in code
+    kernel = ast.compile()
+
+    dh.all_to_gpu()
+    dh.run_kernel(kernel)
+    dh.all_to_cpu()
+
+    np.testing.assert_allclose(dh.gather_array("x")[0, 0], float(func(1.0).evalf()),
+                               rtol=10**-3 if dtype == 'float32' else 10**-5)
+
+
+@pytest.mark.parametrize('a', [sp.Symbol('a'), ps.fields('a:  float64[2d]').center])
+def test_avoid_pow(a):
+    x = ps.fields('x:  float64[2d]')
+
+    up = ps.Assignment(x.center_vector[0], 2 * a ** 2 / 3)
+    ast = ps.create_kernel(up)
+
+    code = ps.get_code_str(ast)
+
+    assert "pow" not in code
+
+
+def test_avoid_pow_fast_div():
+    x = ps.fields('x:  float64[2d]')
+    a = ps.fields('a:  float64[2d]').center
+
+    up = ps.Assignment(x.center_vector[0], fast_division(1, (a**2)))
+    ast = ps.create_kernel(up, config=ps.CreateKernelConfig(target=ps.Target.GPU))
+    # ps.show_code(ast)
+
+    code = ps.get_code_str(ast)
+
+    assert "pow" not in code
+
+
+def test_avoid_pow_move_constants():
+    # At the end of the kernel creation the function move_constants_before_loop will be called
+    # This function additionally contains substitutions for symbols with the same value
+    # Thus it simplifies the equations again
+    x = ps.fields('x:  float64[2d]')
+    a, b, c = sp.symbols("a, b, c")
+
+    up = [ps.Assignment(a, 0.0),
+          ps.Assignment(b, 0.0),
+          ps.Assignment(c, 0.0),
+          ps.Assignment(x.center_vector[0], a**2/18 - a*b/6 - a/18 + b**2/18 + b/18 - c**2/36)]
+    ast = ps.create_kernel(up)
+
+    code = ps.get_code_str(ast)
+    ps.show_code(ast)
+
+    assert "pow" not in code

tests/test_modulo.py

+import pytest
+
+import numpy as np
+import sympy as sp
+import pystencils as ps
+from pystencils.astnodes import LoopOverCoordinate, Conditional, Block, SympyAssignment
+
+SLICE_LIST = [False,
+              ps.make_slice[1:-1:2, 1:-1:2],
+              ps.make_slice[2:-1:2, 4:-1:7],
+              ps.make_slice[4:-1:2, 5:-1:2],
+              ps.make_slice[3:-1:4, 7:-1:3]]
+
+
+@pytest.mark.parametrize('target', [ps.Target.CPU, ps.Target.GPU])
+@pytest.mark.parametrize('iteration_slice', SLICE_LIST)
+def test_mod(target, iteration_slice):
+    if target == ps.Target.GPU:
+        pytest.importorskip("cupy")
+    dh = ps.create_data_handling(domain_size=(51, 51), periodicity=True, default_target=target)
+
+    loop_ctrs = [LoopOverCoordinate.get_loop_counter_symbol(i) for i in range(dh.dim)]
+    cond = [sp.Eq(sp.Mod(loop_ctrs[i], 2), 1) for i in range(dh.dim)]
+
+    field = dh.add_array("a", values_per_cell=1)
+
+    eq_list = [SympyAssignment(field.center, 1.0)]
+
+    if iteration_slice:
+        config = ps.CreateKernelConfig(target=dh.default_target, iteration_slice=iteration_slice)
+        assign = eq_list
+    else:
+        assign = [Conditional(sp.And(*cond), Block(eq_list))]
+        config = ps.CreateKernelConfig(target=dh.default_target)
+
+    kernel = ps.create_kernel(assign, config=config).compile()
+
+    dh.fill(field.name, 0, ghost_layers=True)
+
+    if config.target == ps.enums.Target.GPU:
+        dh.to_gpu(field.name)
+
+    dh.run_kernel(kernel)
+
+    if config.target == ps.enums.Target.GPU:
+        dh.to_cpu(field.name)
+
+    result = dh.gather_array(field.name, ghost_layers=True)
+
+    assert np.all(result[iteration_slice] == 1.0)
+

tests/test_move_constant_before_loop.py

+import numpy as np
+
+import pystencils as ps
+from pystencils.astnodes import Block, LoopOverCoordinate, SympyAssignment, TypedSymbol
+from pystencils.transformations import move_constants_before_loop
+
+
+def test_symbol_renaming():
+    """When two loops have assignments to the same symbol with different rhs and both
+    are pulled before the loops, one of them has to be renamed
+    """
+
+    f, g = ps.fields("f, g : double[2D]")
+    a, b, c = [TypedSymbol(n, np.float64) for n in ('a', 'b', 'c')]
+
+    loop1 = LoopOverCoordinate(Block([SympyAssignment(c, a + b),
+                                      SympyAssignment(g[0, 0], f[0, 0] + c)]),
+                               0, 0, 10)
+    loop2 = LoopOverCoordinate(Block([SympyAssignment(c, a ** 2 + b ** 2),
+                                      SympyAssignment(g[0, 0], f[0, 0] + c)]),
+                               0, 0, 10)
+    block = Block([loop1, loop2])
+
+    move_constants_before_loop(block)
+
+    loops = block.atoms(LoopOverCoordinate)
+    assert len(loops) == 2
+    assert len(block.args[1].body.args) == 1
+    assert len(block.args[3].body.args) == 2
+
+    for loop in loops:
+        assert len(loop.parent.args) == 4  # 2 loops + 2 subexpressions
+        assert loop.parent.args[0].lhs.name != loop.parent.args[2].lhs.name
+
+
+def test_keep_order_of_accesses():
+    f = ps.fields("f: [1D]")
+    x = TypedSymbol("x", np.float64)
+    n = 5
+
+    loop = LoopOverCoordinate(Block([SympyAssignment(x, f[0]),
+                                     SympyAssignment(f[1], 2 * x)]),
+                              0, 0, n)
+    block = Block([loop])
+
+    ps.transformations.resolve_field_accesses(block)
+    new_loops = ps.transformations.cut_loop(loop, [n - 1])
+    ps.transformations.move_constants_before_loop(new_loops.args[1])
+
+    kernel_func = ps.astnodes.KernelFunction(
+        block, ps.Target.CPU, ps.Backend.C, ps.cpu.cpujit.make_python_function, None
+    )
+    kernel = kernel_func.compile()
+
+    print(ps.show_code(kernel_func))
+
+    f_arr = np.ones(n + 1)
+    kernel(f=f_arr)
+
+    print(f_arr)
+
+    assert np.allclose(f_arr, np.array([
+        1, 2, 4, 8, 16, 32
+    ]))

tests/test_nodecollection.py

+import sympy as sp
+
+from pystencils import AssignmentCollection, Assignment
+from pystencils.node_collection import NodeCollection
+from pystencils.astnodes import SympyAssignment
+
+
+def test_node_collection_from_assignment_collection():
+    x = sp.symbols('x')
+    assignment_collection = AssignmentCollection([Assignment(x, 2)])
+    node_collection = NodeCollection.from_assignment_collection(assignment_collection)
+
+    assert node_collection.all_assignments[0] == SympyAssignment(x, 2)

pystencils_tests/test_parameterstudy.py → tests/test_parameterstudy.py

 import io
 import json
-from http.server import HTTPServer, BaseHTTPRequestHandler
+from http.server import BaseHTTPRequestHandler, HTTPServer
 from tempfile import TemporaryDirectory
+
 from pystencils.runhelper import ParameterStudy
 
 

tests/test_phasefield_dentritic_3D.ipynb

+%% Cell type:code id: tags:
+
+``` python
+import pytest
+pytest.importorskip('cupy')
+```
+
+%% Output
+
+    <module 'cupy' from '/home/markus/Python311/lib/python3.11/site-packages/cupy/__init__.py'>
+
+%% Cell type:code id: tags:
+
+``` python
+from pystencils.session import *
+sp.init_printing()
+frac = sp.Rational
+```
+
+%% Cell type:markdown id: tags:
+
+# Phase-field simulation of dentritic solidification in 3D
+
+This notebook tests the model presented in the dentritic growth tutorial in 3D.
+
+%% Cell type:code id: tags:
+
+``` python
+target = ps.Target.GPU
+gpu = target == ps.Target.GPU
+domain_size = (25, 25, 25) if 'is_test_run' in globals() else (300, 300, 300)
+
+dh = ps.create_data_handling(domain_size=domain_size, periodicity=True, default_target=target)
+φ_field = dh.add_array('phi', latex_name='φ')
+φ_field_tmp = dh.add_array('phi_tmp', latex_name='φ_tmp')
+φ_delta_field = dh.add_array('phidelta', latex_name='φ_D')
+t_field = dh.add_array('T')
+t_field_tmp = dh.add_array('T_tmp')
+```
+
+%% Cell type:code id: tags:
+
+``` python
+ε, m, δ, j, θzero, α, γ, Teq, κ, τ = sp.symbols("ε m δ j θ_0 α γ T_eq κ τ")
+εb = sp.Symbol("\\bar{\\epsilon}")
+discretize = ps.fd.Discretization2ndOrder(dx=0.03, dt=1e-5)
+
+φ = φ_field.center
+T = t_field.center
+d = ps.fd.Diff
+
+def f(φ, m):
+    return φ**4 / 4 - (frac(1, 2) - m/3) * φ**3 + (frac(1,4)-m/2)*φ**2
+
+
+
+bulk_free_energy_density = f(φ, m)
+interface_free_energy_density = ε ** 2 / 2 * (d(φ, 0) ** 2 + d(φ, 1) ** 2 + d(φ, 2) ** 2)
+```
+
+%% Cell type:markdown id: tags:
+
+Here comes the major change, that has to be made for the 3D model: $\epsilon$ depends on the interface normal, which can not be computed simply as atan() as in the 2D case
+
+%% Cell type:code id: tags:
+
+``` python
+n = sp.Matrix([d(φ, i) for i in range(3)])
+nLen = sp.sqrt(sum(n_i**2 for n_i in n))
+n = n / nLen
+nVal = sum(n_i**4 for n_i in n)
+σ = δ * nVal
+
+εVal = εb * (1 + σ)
+εVal
+```
+
+%% Output
+
+    $\displaystyle \bar{\epsilon} \left(δ \left(\frac{{\partial_{0} {φ}_{(0,0,0)}}^{4}}{\left({\partial_{0} {φ}_{(0,0,0)}}^{2} + {\partial_{1} {φ}_{(0,0,0)}}^{2} + {\partial_{2} {φ}_{(0,0,0)}}^{2}\right)^{2}} + \frac{{\partial_{1} {φ}_{(0,0,0)}}^{4}}{\left({\partial_{0} {φ}_{(0,0,0)}}^{2} + {\partial_{1} {φ}_{(0,0,0)}}^{2} + {\partial_{2} {φ}_{(0,0,0)}}^{2}\right)^{2}} + \frac{{\partial_{2} {φ}_{(0,0,0)}}^{4}}{\left({\partial_{0} {φ}_{(0,0,0)}}^{2} + {\partial_{1} {φ}_{(0,0,0)}}^{2} + {\partial_{2} {φ}_{(0,0,0)}}^{2}\right)^{2}}\right) + 1\right)$
+                   ⎛  ⎛                            4
+                   ⎜  ⎜                 D(φ[0,0,0])
+    \bar{\epsilon}⋅⎜δ⋅⎜───────────────────────────────────────────── + ───────────
+                   ⎜  ⎜                                            2
+                   ⎜  ⎜⎛           2              2              2⎞    ⎛
+                   ⎝  ⎝⎝D(φ[0,0,0])  + D(φ[0,0,0])  + D(φ[0,0,0]) ⎠    ⎝D(φ[0,0,0]
+    
+                     4                                               4
+          D(φ[0,0,0])                                     D(φ[0,0,0])
+    ────────────────────────────────── + ─────────────────────────────────────────
+                                     2
+     2              2              2⎞    ⎛           2              2
+    )  + D(φ[0,0,0])  + D(φ[0,0,0]) ⎠    ⎝D(φ[0,0,0])  + D(φ[0,0,0])  + D(φ[0,0,0]
+    
+        ⎞    ⎞
+        ⎟    ⎟
+    ────⎟ + 1⎟
+       2⎟    ⎟
+     2⎞ ⎟    ⎟
+    ) ⎠ ⎠    ⎠
+
+%% Cell type:code id: tags:
+
+``` python
+def m_func(temperature):
+    return (α / sp.pi) * sp.atan(γ * (Teq - temperature))
+```
+
+%% Cell type:code id: tags:
+
+``` python
+substitutions = {m: m_func(T),
+                 ε: εVal}
+
+fe_i = interface_free_energy_density.subs(substitutions)
+fe_b = bulk_free_energy_density.subs(substitutions)
+
+μ_if = ps.fd.expand_diff_full(ps.fd.functional_derivative(fe_i, φ), functions=[φ])
+μ_b = ps.fd.expand_diff_full(ps.fd.functional_derivative(fe_b, φ), functions=[φ])
+```
+
+%% Cell type:code id: tags:
+
+``` python
+dF_dφ = μ_b + sp.Piecewise((μ_if, nLen**2 > 1e-10), (0, True))
+```
+
+%% Cell type:code id: tags:
+
+``` python
+parameters = {
+    τ: 0.0003,
+    κ: 1.8,
+    εb: 0.01,
+    δ: 0.3,
+    γ: 10,
+    j: 6,
+    α: 0.9,
+    Teq: 1.0,
+    θzero: 0.2,
+    sp.pi: sp.pi.evalf()
+}
+parameters
+```
+
+%% Output
+
+
+    $\displaystyle \left\{ \pi : 3.14159265358979, \  T_{eq} : 1.0, \  \bar{\epsilon} : 0.01, \  j : 6, \  α : 0.9, \  γ : 10, \  δ : 0.3, \  θ_{0} : 0.2, \  κ : 1.8, \  τ : 0.0003\right\}$
+    {π: 3.14159265358979, T_eq: 1.0, \bar{\epsilon}: 0.01, j: 6, α: 0.9, γ: 10, δ:
+     0.3, θ₀: 0.2, κ: 1.8, τ: 0.0003}
+
+%% Cell type:code id: tags:
+
+``` python
+dφ_dt = - dF_dφ / τ
+assignments = [
+    ps.Assignment(φ_delta_field.center, discretize(dφ_dt.subs(parameters))),
+]
+φEqs = ps.simp.sympy_cse_on_assignment_list(assignments)
+φEqs.append(ps.Assignment(φ_field_tmp.center, discretize(ps.fd.transient(φ) - φ_delta_field.center)))
+
+
+temperatureEvolution = -ps.fd.transient(T) + ps.fd.diffusion(T, 1) + κ * φ_delta_field.center
+temperatureEqs = [
+    ps.Assignment(t_field_tmp.center, discretize(temperatureEvolution.subs(parameters)))
+]
+```
+
+%% Cell type:code id: tags:
+
+``` python
+φ_kernel = ps.create_kernel(φEqs, cpu_openmp=4, target=target).compile()
+temperatureKernel = ps.create_kernel(temperatureEqs, cpu_openmp=4, target=target).compile()
+```
+
+%% Cell type:code id: tags:
+
+``` python
+def time_loop(steps):
+    φ_sync = dh.synchronization_function(['phi'], target=target)
+    temperature_sync = dh.synchronization_function(['T'], target=target)
+    dh.all_to_gpu()
+    for t in range(steps):
+        φ_sync()
+        dh.run_kernel(φ_kernel)
+        temperature_sync()
+        dh.run_kernel(temperatureKernel)
+        dh.swap(φ_field.name, φ_field_tmp.name)
+        dh.swap(t_field.name, t_field_tmp.name)
+    dh.all_to_cpu()
+
+
+def init(nucleus_size=np.sqrt(5)):
+    for b in dh.iterate():
+        x, y, z = b.cell_index_arrays
+        x, y, z = x - b.shape[0] // 2, y - b.shape[1] // 2, z - b.shape[2] // 2
+        b['phi'].fill(0)
+        b['phi'][(x ** 2 + y ** 2 + z ** 2) < nucleus_size ** 2] = 1.0
+        b['T'].fill(0.0)
+
+
+def plot(slice_obj=ps.make_slice[:, :, 0.5]):
+    plt.subplot(1, 3, 1)
+    plt.scalar_field(dh.gather_array('phi', slice_obj).squeeze())
+    plt.title("φ")
+    plt.colorbar()
+    plt.subplot(1, 3, 2)
+    plt.title("T")
+    plt.scalar_field(dh.gather_array('T', slice_obj).squeeze())
+    plt.colorbar()
+    plt.subplot(1, 3, 3)
+    plt.title("∂φ")
+    plt.scalar_field(dh.gather_array('phidelta', slice_obj).squeeze())
+    plt.colorbar()
+```
+
+%% Cell type:code id: tags:
+
+``` python
+init()
+plot()
+print(dh)
+```
+
+%% Output
+
+        Name|      Inner (min/max)|     WithGl (min/max)
+    ----------------------------------------------------
+           T|            (  0,  0)|            (  0,  0)
+       T_tmp|            (  0,  0)|            (  0,  0)
+         phi|            (  0,  1)|            (  0,  1)
+     phi_tmp|            (  0,  0)|            (  0,  0)
+    phidelta|            (  0,  0)|            (  0,  0)
+    
+
+
+
+%% Cell type:code id: tags:
+
+``` python
+if 'is_test_run' in globals():
+    time_loop(2)
+    assert np.isfinite(dh.max('phi'))
+    assert np.isfinite(dh.max('T'))
+    assert np.isfinite(dh.max('phidelta'))
+else:
+    from time import perf_counter
+    vtk_writer = dh.create_vtk_writer('dentritic_growth_large', ['phi'])
+    last = perf_counter()
+    for i in range(4):
+        time_loop(100)
+        vtk_writer(i)
+        print("Step ", i, perf_counter() - last, dh.max('phi'))
+        last = perf_counter()
+```
+
+%% Output
+
+    Step  0 19.713090835999992 1.0
+    Step  1 19.673075279000045 1.0
+    Step  2 19.696444219 1.0
+    Step  3 19.752472744999977 1.0

pystencils_tests/test_pickle_support.py → tests/test_pickle_support.py

-from pystencils import Field, TypedSymbol
 from copy import copy, deepcopy
 
+from pystencils.field import Field
+from pystencils.typing import TypedSymbol
+
 
 def test_field_access():
     field = Field.create_generic('some_field', spatial_dimensions=2, index_dimensions=0)

tests/test_plot.py

+import os
+from tempfile import TemporaryDirectory
+import shutil
+
+import pytest
+
+import numpy as np
+
+import pystencils.plot as plt
+
+
+def example_scalar_field(t=0):
+    x, y = np.meshgrid(np.linspace(0, 2 * np.pi, 100), np.linspace(0, 2 * np.pi, 100))
+    z = np.cos(x + 0.1 * t) * np.sin(y + 0.1 * t) + 0.1 * x * y
+    return z
+
+
+def example_vector_field(t=0, shape=(40, 40)):
+    result = np.empty(shape + (2,))
+    x, y = np.meshgrid(np.linspace(0, 2 * np.pi, shape[0]), np.linspace(0, 2 * np.pi, shape[1]))
+    result[..., 0] = np.cos(x + 0.1 * t) * np.sin(y + 0.1 * t) + 0.01 * x * y
+    result[..., 1] = np.cos(0.001 * y)
+    return result
+
+
+@pytest.mark.skipif(shutil.which('ffmpeg') is None, reason="ffmpeg not available")
+def test_animation():
+    t = 0
+
+    def run_scalar():
+        nonlocal t
+        t += 1
+        return example_scalar_field(t)
+
+    def run_vec():
+        nonlocal t
+        t += 1
+        return example_vector_field(t)
+
+    plt.clf()
+    plt.cla()
+
+    with TemporaryDirectory() as tmp_dir:
+        ani = plt.vector_field_magnitude_animation(run_vec, interval=1, frames=2)
+        ani.save(os.path.join(tmp_dir, "animation1.avi"))
+
+        ani = plt.vector_field_animation(run_vec, interval=1, frames=2, rescale=True)
+        ani.save(os.path.join(tmp_dir, "animation2.avi"))
+
+        ani = plt.vector_field_animation(run_vec, interval=1, frames=2, rescale=False)
+        ani.save(os.path.join(tmp_dir, "animation3.avi"))
+
+        ani = plt.scalar_field_animation(run_scalar, interval=1, frames=2, rescale=True)
+        ani.save(os.path.join(tmp_dir, "animation4.avi"))
+
+        ani = plt.scalar_field_animation(run_scalar, interval=1, frames=2, rescale=False)
+        ani.save(os.path.join(tmp_dir, "animation5.avi"))
+
+        ani = plt.surface_plot_animation(run_scalar, frames=2)
+        ani.save(os.path.join(tmp_dir, "animation6.avi"))

tests/test_printing.py

+import pytest
+import re
+import sympy as sp
+
+import pystencils
+from pystencils.backends.cbackend import CBackend
+
+
+class UnsupportedNode(pystencils.astnodes.Node):
+
+    def __init__(self):
+        super().__init__()
+
+
+@pytest.mark.parametrize('type', ('float32', 'float64', 'int64'))
+@pytest.mark.parametrize('negative', (False, 'Negative'))
+@pytest.mark.parametrize('target', (pystencils.Target.CPU, pystencils.Target.GPU))
+def test_print_infinity(type, negative, target):
+
+    x = pystencils.fields(f'x:  {type}[1d]')
+
+    if negative:
+        assignment = pystencils.Assignment(x.center, -sp.oo)
+    else:
+        assignment = pystencils.Assignment(x.center, sp.oo)
+    ast = pystencils.create_kernel(assignment, data_type=type, target=target)
+
+    if target == pystencils.Target.GPU:
+        pytest.importorskip('cupy')
+
+    ast.compile()
+
+    print(ast.compile().code)
+
+
+def test_print_unsupported_node():
+    with pytest.raises(NotImplementedError, match='CBackend does not support node of type UnsupportedNode'):
+        CBackend()(UnsupportedNode())
+
+
+@pytest.mark.parametrize('dtype', ('float32', 'float64'))
+@pytest.mark.parametrize('target', (pystencils.Target.CPU, pystencils.Target.GPU))
+def test_print_subtraction(dtype, target):
+    a, b, c = sp.symbols("a b c")
+
+    x = pystencils.fields(f'x: {dtype}[3d]')
+    y = pystencils.fields(f'y: {dtype}[3d]')
+
+    config = pystencils.CreateKernelConfig(target=target, data_type=dtype)
+    update = pystencils.Assignment(x.center, y.center - a * b ** 8 + b * -1 / 42.0 - 2 * c ** 4)
+    ast = pystencils.create_kernel(update, config=config)
+
+    code = pystencils.get_code_str(ast)
+    assert "-1.0" not in code
+
+
+def test_print_small_integer_pow():
+    printer = pystencils.backends.cbackend.CBackend()
+
+    x = sp.Symbol("x")
+    y = sp.Symbol("y")
+    n = pystencils.TypedSymbol("n", "int")
+    t = pystencils.TypedSymbol("t", "float32")
+    s = pystencils.TypedSymbol("s", "float32")
+
+    equs = [
+        pystencils.astnodes.SympyAssignment(y, 1/x),
+        pystencils.astnodes.SympyAssignment(y, x*x),
+        pystencils.astnodes.SympyAssignment(y, 1/(x*x)),
+        pystencils.astnodes.SympyAssignment(y, x**8),
+        pystencils.astnodes.SympyAssignment(y, x**(-8)),
+        pystencils.astnodes.SympyAssignment(y, x**9),
+        pystencils.astnodes.SympyAssignment(y, x**(-9)),
+        pystencils.astnodes.SympyAssignment(y, x**n),
+        pystencils.astnodes.SympyAssignment(y, sp.Pow(4, 4, evaluate=False)),
+        pystencils.astnodes.SympyAssignment(y, x**0.25),
+        pystencils.astnodes.SympyAssignment(y, x**y),
+        pystencils.astnodes.SympyAssignment(y, pystencils.typing.cast_functions.CastFunc(1/x, "float32")),
+        pystencils.astnodes.SympyAssignment(y, pystencils.typing.cast_functions.CastFunc(x*x, "float32")),
+        pystencils.astnodes.SympyAssignment(y, (t+s)**(-8)),
+        pystencils.astnodes.SympyAssignment(y, (t+s)**(-9)),
+    ]
+    typed = pystencils.typing.transformations.add_types(equs, pystencils.CreateKernelConfig())
+
+    regexes = [
+        r"1\.0\s*/\s*\(?\s*x\s*\)?",
+        r"x\s*\*\s*x",
+        r"1\.0\s*/\s*\(\s*x\s*\*x\s*\)",
+        r"x(\s*\*\s*x){7}",
+        r"1\.0\s*/\s*\(\s*x(\s*\*\s*x){7}\s*\)",
+        r"pow\(\s*x\s*,\s*9(\.0)?\s*\)",
+        r"pow\(\s*x\s*,\s*-9(\.0)?\s*\)",
+        r"pow\(\s*x\s*,\s*\(?\s*\(\s*double\s*\)\s*\(\s*n\s*\)\s*\)?\s*\)",
+        r"\(\s*int[a-zA-Z0-9_]*\s*\)\s*\(+\s*4(\s*\*\s*4){3}\s*\)+",
+        r"pow\(\s*x\s*,\s*0\.25\s*\)",
+        r"pow\(\s*x\s*,\s*y\s*\)",
+        r"\(\s*float\s*\)[ ()]*1\.0\s*/\s*\(?\s*x\s*\)?",
+        r"\(\s*float\s*\)[ ()]*x\s*\*\s*x",
+        r"\(\s*float\s*\)\s*\(\s*1\.0f\s*/\s*\(\s*\(\s*s\s*\+\s*t\s*\)(\s*\*\s*\(\s*s\s*\+\s*t\s*\)){7}\s*\)",
+        r"powf\(\s*s\s*\+\s*t\s*,\s*-9\.0f\s*\)",
+    ]
+
+    for r, e in zip(regexes, typed):
+        assert re.search(r, printer(e))

tests/test_quicktests.py

+import numpy as np
+
+import pystencils as ps
+from pystencils.cpu.vectorization import get_supported_instruction_sets
+from pystencils.cpu.vectorization import replace_inner_stride_with_one, vectorize
+
+
+def test_basic_kernel():
+    for domain_shape in [(4, 5), (3, 4, 5)]:
+        dh = ps.create_data_handling(domain_size=domain_shape, periodicity=True)
+        assert all(dh.periodicity)
+
+        f = dh.add_array('f', values_per_cell=1)
+        tmp = dh.add_array('tmp', values_per_cell=1)
+
+        stencil_2d = [(1, 0), (-1, 0), (0, 1), (0, -1)]
+        stencil_3d = [(1, 0, 0), (-1, 0, 0), (0, 1, 0), (0, -1, 0), (0, 0, 1), (0, 0, -1)]
+        stencil = stencil_2d if dh.dim == 2 else stencil_3d
+
+        jacobi = ps.Assignment(tmp.center, sum(f.neighbors(stencil)) / len(stencil))
+        kernel = ps.create_kernel(jacobi).compile()
+
+        for b in dh.iterate(ghost_layers=1):
+            b['f'].fill(42)
+        dh.run_kernel(kernel)
+        for b in dh.iterate(ghost_layers=0):
+            np.testing.assert_equal(b['f'], 42)
+
+        float_seq = [1.0, 2.0, 3.0, 4.0]
+        int_seq = [1, 2, 3]
+        for op in ('min', 'max', 'sum'):
+            assert (dh.reduce_float_sequence(float_seq, op) == float_seq).all()
+            assert (dh.reduce_int_sequence(int_seq, op) == int_seq).all()
+
+
+def test_basic_blocking_staggered():
+    f = ps.fields("f: double[2D]")
+    stag = ps.fields("stag(2): double[2D]", field_type=ps.FieldType.STAGGERED)
+    terms = [
+       f[0, 0] - f[-1, 0],
+       f[0, 0] - f[0, -1],
+    ]
+    assignments = [ps.Assignment(stag.staggered_access(d), terms[i]) for i, d in enumerate(stag.staggered_stencil)]
+    kernel = ps.create_staggered_kernel(assignments, cpu_blocking=(3, 16)).compile()
+    reference_kernel = ps.create_staggered_kernel(assignments).compile()
+
+    f_arr = np.random.rand(80, 33)
+    stag_arr = np.zeros((80, 33, 3))
+    stag_ref = np.zeros((80, 33, 3))
+    kernel(f=f_arr, stag=stag_arr)
+    reference_kernel(f=f_arr, stag=stag_ref)
+    np.testing.assert_almost_equal(stag_arr, stag_ref)
+
+
+def test_basic_vectorization():
+    supported_instruction_sets = get_supported_instruction_sets()
+    if supported_instruction_sets:
+        instruction_set = supported_instruction_sets[-1]
+    else:
+        instruction_set = None
+
+    f, g = ps.fields("f, g : double[2D]")
+    update_rule = [ps.Assignment(g[0, 0], f[0, 0] + f[-1, 0] + f[1, 0] + f[0, 1] + f[0, -1] + 42.0)]
+    ast = ps.create_kernel(update_rule)
+
+    replace_inner_stride_with_one(ast)
+    vectorize(ast, instruction_set=instruction_set)
+    func = ast.compile()
+
+    arr = np.ones((23 + 2, 17 + 2)) * 5.0
+    dst = np.zeros_like(arr)
+
+    func(g=dst, f=arr)
+    np.testing.assert_equal(dst[1:-1, 1:-1], 5 * 5.0 + 42.0)
\ No newline at end of file

tests/test_random.py

+import numpy as np
+
+import pytest
+
+import pystencils as ps
+from pystencils.astnodes import SympyAssignment
+from pystencils.node_collection import NodeCollection
+from pystencils.rng import PhiloxFourFloats, PhiloxTwoDoubles, AESNIFourFloats, AESNITwoDoubles, random_symbol
+from pystencils.backends.simd_instruction_sets import get_supported_instruction_sets
+from pystencils.cpu.cpujit import get_compiler_config
+from pystencils.typing import TypedSymbol
+from pystencils.enums import Target
+
+RNGs = {('philox', 'float'): PhiloxFourFloats, ('philox', 'double'): PhiloxTwoDoubles,
+        ('aesni', 'float'): AESNIFourFloats, ('aesni', 'double'): AESNITwoDoubles}
+
+instruction_sets = get_supported_instruction_sets()
+if get_compiler_config()['os'] == 'windows':
+    # skip instruction sets supported by the CPU but not by the compiler
+    if 'avx' in instruction_sets and ('/arch:avx2' not in get_compiler_config()['flags'].lower()
+                                      and '/arch:avx512' not in get_compiler_config()['flags'].lower()):
+        instruction_sets.remove('avx')
+    if 'avx512' in instruction_sets and '/arch:avx512' not in get_compiler_config()['flags'].lower():
+        instruction_sets.remove('avx512')
+    if 'avx512vl' in instruction_sets and '/arch:avx512' not in get_compiler_config()['flags'].lower():
+        instruction_sets.remove('avx512vl')
+
+
+@pytest.mark.parametrize('target, rng', ((Target.CPU, 'philox'), (Target.CPU, 'aesni'), (Target.GPU, 'philox')))
+@pytest.mark.parametrize('precision', ('float', 'double'))
+@pytest.mark.parametrize('dtype', ('float', 'double'))
+def test_rng(target, rng, precision, dtype, t=124, offsets=(0, 0), keys=(0, 0), offset_values=None):
+    if target == Target.GPU:
+        pytest.importorskip('cupy')
+    if instruction_sets and {'neon', 'sve', 'sve2', 'sme', 'vsx', 'rvv'}.intersection(instruction_sets) and rng == 'aesni':
+        pytest.xfail('AES not yet implemented for this architecture')
+    if rng == 'aesni' and len(keys) == 2:
+        keys *= 2
+    if offset_values is None:
+        offset_values = offsets
+
+    dh = ps.create_data_handling((2, 2), default_ghost_layers=0, default_target=target)
+    f = dh.add_array("f", values_per_cell=4 if precision == 'float' else 2,
+                     dtype=np.float32 if dtype == 'float' else np.float64)
+    dh.fill(f.name, 42.0)
+
+    rng_node = RNGs[(rng, precision)](dh.dim, offsets=offsets, keys=keys)
+    assignments = [rng_node] + [SympyAssignment(f(i), s) for i, s in enumerate(rng_node.result_symbols)]
+    kernel = ps.create_kernel(assignments, target=dh.default_target).compile()
+
+    dh.all_to_gpu()
+    kwargs = {'time_step': t}
+    if offset_values != offsets:
+        kwargs.update({k.name: v for k, v in zip(offsets, offset_values)})
+    dh.run_kernel(kernel, **kwargs)
+    dh.all_to_cpu()
+    arr = dh.gather_array(f.name)
+    assert np.logical_and(arr <= 1.0, arr >= 0).all()
+
+    if rng == 'philox' and t == 124 and offsets == (0, 0) and keys == (0, 0) and dh.shape == (2, 2):
+        int_reference = np.array([[[3576608082, 1252663339, 1987745383, 348040302],
+                                   [1032407765, 970978240, 2217005168, 2424826293]],
+                                  [[2958765206, 3725192638, 2623672781, 1373196132],
+                                   [850605163, 1694561295, 3285694973, 2799652583]]])
+    else:
+        pytest.importorskip('randomgen')
+        if rng == 'aesni':
+            from randomgen import AESCounter
+            int_reference = np.empty(dh.shape + (4,), dtype=int)
+            for x in range(dh.shape[0]):
+                for y in range(dh.shape[1]):
+                    r = AESCounter(counter=t + (x + offset_values[0]) * 2 ** 32 + (y + offset_values[1]) * 2 ** 64,
+                                   key=keys[0] + keys[1] * 2 ** 32 + keys[2] * 2 ** 64 + keys[3] * 2 ** 96,
+                                   mode="sequence")
+                    a, b = r.random_raw(size=2)
+                    int_reference[x, y, :] = [a % 2 ** 32, a // 2 ** 32, b % 2 ** 32, b // 2 ** 32]
+        else:
+            from randomgen import Philox
+            int_reference = np.empty(dh.shape + (4,), dtype=int)
+            for x in range(dh.shape[0]):
+                for y in range(dh.shape[1]):
+                    r = Philox(counter=t + (x + offset_values[0]) * 2 ** 32 + (y + offset_values[1]) * 2 ** 64 - 1,
+                               key=keys[0] + keys[1] * 2 ** 32, number=4, width=32, mode="sequence")
+                    int_reference[x, y, :] = r.random_raw(size=4)
+
+    if precision == 'float' or dtype == 'float':
+        eps = np.finfo(np.float32).eps
+    else:
+        eps = np.finfo(np.float64).eps
+    if rng == 'aesni':  # precision appears to be slightly worse
+        eps = max(1e-12, 2 * eps)
+
+    if precision == 'float':
+        reference = int_reference * 2. ** -32 + 2. ** -33
+    else:
+        x = int_reference[:, :, 0::2]
+        y = int_reference[:, :, 1::2]
+        z = x ^ y << (53 - 32)
+        reference = z * 2. ** -53 + 2. ** -54
+    assert np.allclose(arr, reference, rtol=0, atol=eps)
+
+
+@pytest.mark.parametrize('vectorized', (False, True))
+@pytest.mark.parametrize('kind', ('value', 'symbol'))
+def test_rng_offsets(kind, vectorized):
+    if vectorized:
+        test = test_rng_vectorized
+        if not instruction_sets:
+            pytest.skip("cannot detect CPU instruction set")
+    else:
+        test = test_rng
+    if kind == 'value':
+        test(instruction_sets[-1] if vectorized else Target.CPU, 'philox', 'float', 'float', t=8,
+             offsets=(6, 7), keys=(5, 309))
+    elif kind == 'symbol':
+        offsets = (TypedSymbol("x0", np.uint32), TypedSymbol("y0", np.uint32))
+        test(instruction_sets[-1] if vectorized else Target.GPU, 'philox', 'float', 'float', t=8,
+             offsets=offsets, offset_values=(6, 7), keys=(5, 309))
+
+
+@pytest.mark.parametrize('target', instruction_sets)
+@pytest.mark.parametrize('rng', ('philox', 'aesni'))
+@pytest.mark.parametrize('precision,dtype', (('float', 'float'), ('double', 'double')))
+def test_rng_vectorized(target, rng, precision, dtype, t=130, offsets=(1, 3), keys=(0, 0), offset_values=None):
+    if (target in ['neon', 'vsx', 'rvv', 'sme'] or target.startswith('sve')) and rng == 'aesni':
+        pytest.xfail('AES not yet implemented for this architecture')
+    cpu_vectorize_info = {'assume_inner_stride_one': True, 'assume_aligned': True, 'instruction_set': target}
+
+    dh = ps.create_data_handling((131, 131), default_ghost_layers=0, default_target=Target.CPU)
+    f = dh.add_array("f", values_per_cell=4 if precision == 'float' else 2,
+                     dtype=np.float32 if dtype == 'float' else np.float64, alignment=True)
+    dh.fill(f.name, 42.0)
+    ref = dh.add_array("ref", values_per_cell=4 if precision == 'float' else 2)
+
+    rng_node = RNGs[(rng, precision)](dh.dim, offsets=offsets)
+    assignments = [rng_node] + [SympyAssignment(ref(i), s) for i, s in enumerate(rng_node.result_symbols)]
+    kernel = ps.create_kernel(assignments, target=dh.default_target).compile()
+
+    kwargs = {'time_step': t}
+    if offset_values is not None:
+        kwargs.update({k.name: v for k, v in zip(offsets, offset_values)})
+    dh.run_kernel(kernel, **kwargs)
+
+    rng_node = RNGs[(rng, precision)](dh.dim, offsets=offsets)
+    assignments = [rng_node] + [SympyAssignment(f(i), s) for i, s in enumerate(rng_node.result_symbols)]
+    kernel = ps.create_kernel(assignments, target=dh.default_target, cpu_vectorize_info=cpu_vectorize_info).compile()
+
+    dh.run_kernel(kernel, **kwargs)
+
+    ref_data = dh.gather_array(ref.name)
+    data = dh.gather_array(f.name)
+
+    assert np.allclose(ref_data, data)
+
+
+@pytest.mark.parametrize('vectorized', (False, True))
+def test_rng_symbol(vectorized):
+    """Make sure that the RNG symbol generator generates symbols and that the resulting code compiles"""
+    cpu_vectorize_info = None
+    if vectorized:
+        if not instruction_sets:
+            pytest.skip("cannot detect CPU instruction set")
+        else:
+            cpu_vectorize_info = {'assume_inner_stride_one': True, 'assume_aligned': True,
+                                  'instruction_set': instruction_sets[-1]}
+
+    dh = ps.create_data_handling((8, 8), default_ghost_layers=0, default_target=Target.CPU)
+    f = dh.add_array("f", values_per_cell=2 * dh.dim, alignment=True)
+    nc = NodeCollection([SympyAssignment(f(i), 0) for i in range(f.shape[-1])])
+    subexpressions = []
+    rng_symbol_gen = random_symbol(subexpressions, dim=dh.dim)
+    for i in range(f.shape[-1]):
+        nc.all_assignments[i] = SympyAssignment(nc.all_assignments[i].lhs, next(rng_symbol_gen))
+    symbols = [a.rhs for a in nc.all_assignments]
+    [nc.all_assignments.insert(0, subexpression) for subexpression in subexpressions]
+    assert len(symbols) == f.shape[-1] and len(set(symbols)) == f.shape[-1]
+    ps.create_kernel(nc, target=dh.default_target, cpu_vectorize_info=cpu_vectorize_info).compile()
+
+
+@pytest.mark.parametrize('vectorized', (False, True))
+def test_staggered(vectorized):
+    """Make sure that the RNG counter can be substituted during loop cutting"""
+
+    dh = ps.create_data_handling((8, 8), default_ghost_layers=0, default_target=Target.CPU)
+    j = dh.add_array("j", values_per_cell=dh.dim, field_type=ps.FieldType.STAGGERED_FLUX)
+    a = ps.AssignmentCollection([ps.Assignment(j.staggered_access(n), 0) for n in j.staggered_stencil])
+    rng_symbol_gen = random_symbol(a.subexpressions, dim=dh.dim, rng_node=PhiloxTwoDoubles)
+    a.main_assignments[0] = ps.Assignment(a.main_assignments[0].lhs, next(rng_symbol_gen))
+    kernel = ps.create_staggered_kernel(a, target=dh.default_target).compile()
+
+    if not vectorized:
+        return
+    if not instruction_sets:
+        pytest.skip("cannot detect CPU instruction set")
+    pytest.importorskip('islpy')
+    cpu_vectorize_info = {'assume_inner_stride_one': True, 'assume_aligned': False,
+                          'instruction_set': instruction_sets[-1]}
+
+    dh.fill(j.name, 867)
+    dh.run_kernel(kernel, seed=5, time_step=309)
+    ref_data = dh.gather_array(j.name)
+
+    kernel2 = ps.create_staggered_kernel(a, target=dh.default_target, cpu_vectorize_info=cpu_vectorize_info).compile()
+
+    dh.fill(j.name, 867)
+    dh.run_kernel(kernel2, seed=5, time_step=309)
+    data = dh.gather_array(j.name)
+
+    assert np.allclose(ref_data, data)

tests/test_sharedmethodcache.py

+from pystencils.cache import sharedmethodcache
+
+
+class Fib:
+
+    def __init__(self):
+        self.fib_rec_called = 0
+        self.fib_iter_called = 0
+
+    @sharedmethodcache("fib_cache")
+    def fib_rec(self, n):
+        self.fib_rec_called += 1
+        return 1 if n <= 1 else self.fib_rec(n-1) + self.fib_rec(n-2)
+
+    @sharedmethodcache("fib_cache")
+    def fib_iter(self, n):
+        self.fib_iter_called += 1
+        f1, f2 = 0, 1
+        for i in range(n):
+            f2 = f1 + f2
+            f1 = f2 - f1
+        return f2
+
+
+def test_fib_memoization_1():
+    fib = Fib()
+
+    assert "fib_cache" not in fib.__dict__
+
+    f13 = fib.fib_rec(13)
+    assert fib.fib_rec_called == 14
+    assert "fib_cache" in fib.__dict__
+    assert fib.fib_cache[(13,)] == f13
+
+    for k in range(14):
+        #   fib_iter should use cached results from fib_rec
+        fib.fib_iter(k)
+    
+    assert fib.fib_iter_called == 0
+
+
+def test_fib_memoization_2():
+    fib = Fib()
+
+    f11 = fib.fib_iter(11)
+    f12 = fib.fib_iter(12)
+
+    assert fib.fib_iter_called == 2
+
+    f13 = fib.fib_rec(13)
+
+    #   recursive calls should be cached
+    assert fib.fib_rec_called == 1
+
+
+class Triad:
+    
+    def __init__(self):
+        self.triad_called = 0
+
+    @sharedmethodcache("triad_cache")
+    def triad(self, a, b, c=0):
+        """Computes the triad a*b+c."""
+        self.triad_called += 1
+        return a * b + c
+
+
+def test_triad_memoization():
+    triad = Triad()
+
+    assert triad.triad.__doc__ == "Computes the triad a*b+c."
+
+    t = triad.triad(12, 4, 15)
+    assert triad.triad_called == 1
+    assert triad.triad_cache[(12, 4, 15)] == t
+
+    t = triad.triad(12, 4, c=15)
+    assert triad.triad_called == 2
+    assert triad.triad_cache[(12, 4, 'c', 15)] == t
+
+    t = triad.triad(12, 4, 15)
+    assert triad.triad_called == 2
+
+    t = triad.triad(12, 4, c=15)
+    assert triad.triad_called == 2

pystencils_tests/test_simplification_strategy.py → tests/test_simplification_strategy.py

 import sympy as sp
+
+import pystencils as ps
 from pystencils import Assignment, AssignmentCollection
-from pystencils.simp import SimplificationStrategy, apply_on_all_subexpressions, \
-    subexpression_substitution_in_existing_subexpressions
+from pystencils.simp import (
+    SimplificationStrategy, apply_on_all_subexpressions,
+    subexpression_substitution_in_existing_subexpressions)
 
 
 def test_simplification_strategy():
@@ -27,7 +30,7 @@ def test_simplification_strategy():
 
     result = strategy(ac)
     assert result.operation_count['adds'] == 7
-    assert result.operation_count['muls'] == 5
+    assert result.operation_count['muls'] == 4
     assert result.operation_count['divs'] == 0
 
     # Trigger display routines, such that they are at least executed
@@ -41,3 +44,45 @@ def test_simplification_strategy():
     assert 'Adds' in report._repr_html_()
 
     assert 'factor' in str(strategy)
+
+
+def test_split_inner_loop():
+    dst = ps.fields('dst(8): double[2D]')
+    s = sp.symbols('s_:8')
+    x = sp.symbols('x')
+    subexpressions = []
+    main = [
+        Assignment(dst[0, 0](0), s[0]),
+        Assignment(dst[0, 0](1), s[1]),
+        Assignment(dst[0, 0](2), s[2]),
+        Assignment(dst[0, 0](3), s[3]),
+        Assignment(dst[0, 0](4), s[4]),
+        Assignment(dst[0, 0](5), s[5]),
+        Assignment(dst[0, 0](6), s[6]),
+        Assignment(dst[0, 0](7), s[7]),
+        Assignment(x, sum(s))
+    ]
+    ac = AssignmentCollection(main, subexpressions)
+    split_groups = [[dst[0, 0](0), dst[0, 0](1)],
+                    [dst[0, 0](2), dst[0, 0](3)],
+                    [dst[0, 0](4), dst[0, 0](5)],
+                    [dst[0, 0](6), dst[0, 0](7), x]]
+    ac.simplification_hints['split_groups'] = split_groups
+    ast = ps.create_kernel(ac)
+
+    code = ps.get_code_str(ast)
+    ps.show_code(ast)
+    # we have four inner loops as indicated in split groups (4 elements) plus one outer loop
+    assert code.count('for') == 5
+    ast = ps.create_kernel(ac, target=ps.Target.GPU)
+
+    code = ps.get_code_str(ast)
+    # on GPUs is wouldn't be good to use loop splitting
+    assert code.count('for') == 0
+
+    ac = AssignmentCollection(main, subexpressions)
+    ast = ps.create_kernel(ac)
+
+    code = ps.get_code_str(ast)
+    # one inner loop and one outer loop
+    assert code.count('for') == 2

tests/test_simplifications.py

+from sys import version_info as vs
+import pytest
+
+import pystencils.config
+import sympy as sp
+import pystencils as ps
+
+from pystencils import Assignment, AssignmentCollection, fields
+from pystencils.simp import subexpression_substitution_in_main_assignments
+from pystencils.simp import add_subexpressions_for_divisions
+from pystencils.simp import add_subexpressions_for_sums
+from pystencils.simp import add_subexpressions_for_field_reads
+from pystencils.simp.simplifications import add_subexpressions_for_constants
+from pystencils.typing import BasicType, TypedSymbol
+
+a, b, c, d, x, y, z = sp.symbols("a b c d x y z")
+s0, s1, s2, s3 = sp.symbols("s_:4")
+f = sp.symbols("f_:9")
+
+
+def test_subexpression_substitution_in_main_assignments():
+    subexpressions = [
+        Assignment(s0, 2 * a + 2 * b),
+        Assignment(s1, 2 * a + 2 * b + 2 * c),
+        Assignment(s2, 2 * a + 2 * b + 2 * c + 2 * d),
+        Assignment(s3, 2 * a + 2 * b * c),
+        Assignment(x, s1 + s2 + s0 + s3)
+    ]
+    main = [
+        Assignment(f[0], s1 + s2 + s0 + s3),
+        Assignment(f[1], s1 + s2 + s0 + s3),
+        Assignment(f[2], s1 + s2 + s0 + s3),
+        Assignment(f[3], s1 + s2 + s0 + s3),
+        Assignment(f[4], s1 + s2 + s0 + s3)
+    ]
+    ac = AssignmentCollection(main, subexpressions)
+    ac = subexpression_substitution_in_main_assignments(ac)
+    for i in range(0, len(ac.main_assignments)):
+        assert ac.main_assignments[i].rhs == x
+
+
+def test_add_subexpressions_for_divisions():
+    subexpressions = [
+        Assignment(s0, 2 / a + 2 / b),
+        Assignment(s1, 2 / a + 2 / b + 2 / c),
+        Assignment(s2, 2 / a + 2 / b + 2 / c + 2 / d),
+        Assignment(s3, 2 / a + 2 / b / c),
+        Assignment(x, s1 + s2 + s0 + s3)
+    ]
+    main = [
+        Assignment(f[0], s1 + s2 + s0 + s3)
+    ]
+    ac = AssignmentCollection(main, subexpressions)
+    divs_before_optimisation = ac.operation_count["divs"]
+    ac = add_subexpressions_for_divisions(ac)
+    divs_after_optimisation = ac.operation_count["divs"]
+    assert divs_before_optimisation - divs_after_optimisation == 8
+    rhs = []
+    for i in range(len(ac.subexpressions)):
+        rhs.append(ac.subexpressions[i].rhs)
+
+    assert 1/a in rhs
+    assert 1/b in rhs
+    assert 1/c in rhs
+    assert 1/d in rhs
+
+
+def test_add_subexpressions_for_constants():
+    half = sp.Rational(1,2)
+    sqrt_2 = sp.sqrt(2)
+    main = [
+        Assignment(f[0], half * a + half * b + half * c),
+        Assignment(f[1], - half * a - half * b),
+        Assignment(f[2], a * sqrt_2 - b * sqrt_2),
+        Assignment(f[3], a**2 + b**2)
+    ]
+    ac = AssignmentCollection(main)
+    ac = add_subexpressions_for_constants(ac)
+    
+    assert len(ac.subexpressions) == 2
+    
+    half_subexp = None
+    sqrt_subexp = None
+
+    for asm in ac.subexpressions:
+        if asm.rhs == half:
+            half_subexp = asm.lhs
+        elif asm.rhs == sqrt_2:
+            sqrt_subexp = asm.lhs
+        else:
+            pytest.fail(f"An unexpected subexpression was encountered: {asm}")
+            
+    assert half_subexp is not None
+    assert sqrt_subexp is not None
+    
+    for asm in ac.main_assignments[:3]:
+        assert isinstance(asm.rhs, sp.Mul)
+
+    assert any(arg == half_subexp for arg in ac.main_assignments[0].rhs.args)
+    assert any(arg == half_subexp for arg in ac.main_assignments[1].rhs.args)
+    assert any(arg == sqrt_subexp for arg in ac.main_assignments[2].rhs.args)
+
+    #   Do not replace exponents!
+    assert ac.main_assignments[3].rhs == a**2 + b**2
+
+
+def test_add_subexpressions_for_sums():
+    subexpressions = [
+        Assignment(s0, a + b + c + d),
+        Assignment(s1, 3 * a * sp.sqrt(x) + 4 * b + c),
+        Assignment(s2, 3 * a * sp.sqrt(x) + 4 * b + c),
+        Assignment(s3, 3 * a * sp.sqrt(x) + 4 * b + c)
+    ]
+    main = [
+        Assignment(f[0], s1 + s2 + s0 + s3)
+    ]
+    ac = AssignmentCollection(main, subexpressions)
+    ops_before_optimisation = ac.operation_count
+    ac = add_subexpressions_for_sums(ac)
+    ops_after_optimisation = ac.operation_count
+    assert ops_after_optimisation["adds"] == ops_before_optimisation["adds"]
+    assert ops_after_optimisation["muls"] < ops_before_optimisation["muls"]
+    assert ops_after_optimisation["sqrts"] < ops_before_optimisation["sqrts"]
+
+    rhs = []
+    for i in range(len(ac.subexpressions)):
+        rhs.append(ac.subexpressions[i].rhs)
+
+    assert a + b + c + d in rhs
+    assert 3 * a * sp.sqrt(x) in rhs
+
+
+def test_add_subexpressions_for_field_reads():
+    s, v = fields("s(5), v(5): double[2D]")
+    subexpressions = []
+
+    main = [Assignment(s[0, 0](0), 3 * v[0, 0](0)),
+            Assignment(s[0, 0](1), 10 * v[0, 0](1))]
+
+    ac = AssignmentCollection(main, subexpressions)
+    assert len(ac.subexpressions) == 0
+    ac2 = add_subexpressions_for_field_reads(ac)
+    assert len(ac2.subexpressions) == 2
+    ac3 = add_subexpressions_for_field_reads(ac, data_type="float32")
+    assert len(ac3.subexpressions) == 2
+    assert isinstance(ac3.subexpressions[0].lhs, TypedSymbol)
+    assert ac3.subexpressions[0].lhs.dtype == BasicType("float32")
+
+    # added check for early out of add_subexpressions_for_field_reads is no fields appear on the rhs (See #92)
+    main = [Assignment(s[0, 0](0), 3.0),
+            Assignment(s[0, 0](1), 4.0)]
+
+    ac4 = AssignmentCollection(main, subexpressions)
+    assert len(ac4.subexpressions) == 0
+    ac5 = add_subexpressions_for_field_reads(ac4)
+    assert ac5 is not None
+    assert ac4 is ac5
+
+
+@pytest.mark.parametrize('target', (ps.Target.CPU, ps.Target.GPU))
+@pytest.mark.parametrize('dtype', ('float32', 'float64'))
+@pytest.mark.skipif((vs.major, vs.minor, vs.micro) == (3, 8, 2), reason="does not work on python 3.8.2 for some reason")
+def test_sympy_optimizations(target, dtype):
+    if target == ps.Target.GPU:
+        pytest.importorskip("cupy")
+    src, dst = ps.fields(f'src, dst:  {dtype}[2d]')
+
+    assignments = ps.AssignmentCollection({
+        src[0, 0]: 1.0 * (sp.exp(dst[0, 0]) - 1)
+    })
+
+    config = pystencils.config.CreateKernelConfig(target=target, default_number_float=dtype)
+    ast = ps.create_kernel(assignments, config=config)
+
+    ps.show_code(ast)
+
+    code = ps.get_code_str(ast)
+    if dtype == 'float32':
+        assert 'expf(' in code
+    elif dtype == 'float64':
+        assert 'exp(' in code
+
+
+@pytest.mark.parametrize('target', (ps.Target.CPU, ps.Target.GPU))
+@pytest.mark.parametrize('simplification', (True, False))
+@pytest.mark.skipif((vs.major, vs.minor, vs.micro) == (3, 8, 2), reason="does not work on python 3.8.2 for some reason")
+def test_evaluate_constant_terms(target, simplification):
+    if target == ps.Target.GPU:
+        pytest.importorskip("cupy")
+    src, dst = ps.fields('src, dst:  float32[2d]')
+
+    # cos of a number will always be simplified
+    assignments = ps.AssignmentCollection({
+        src[0, 0]: -sp.cos(1) + dst[0, 0]
+    })
+
+    config = pystencils.config.CreateKernelConfig(target=target, default_assignment_simplifications=simplification)
+    ast = ps.create_kernel(assignments, config=config)
+    code = ps.get_code_str(ast)
+    assert 'cos(' not in code