Fix: Wrong fString in Cuda Backend

Due to changing the string formating in pystencils, an error occurred in the CUDA backend, which is fixed by changing back to the classical string formating.

Furthermore, I added a compile instruction to test_fast_approximation to catch the error in the test cases, which was thrown at compile time in the pygrandchem module.

pystencils/backends/cuda_backend.py

@@ -33,10 +33,11 @@ class CudaBackend(CBackend):
         super().__init__(sympy_printer, signature_only, dialect='cuda')
 
     def _print_SharedMemoryAllocation(self, node):
-        code = "__shared__ {dtype} {name}[{num_elements}];"
-        return code.format(dtype=node.symbol.dtype,
-                           name=self.sympy_printer.doprint(node.symbol.name),
-                           num_elements='*'.join([str(s) for s in node.shared_mem.shape]))
+        dtype = node.symbol.dtype
+        name = self.sympy_printer.doprint(node.symbol.name)
+        num_elements = '*'.join([str(s) for s in node.shared_mem.shape])
+        code = f"__shared__ {dtype} {name}[{num_elements}];"
+        return code
 
     @staticmethod
     def _print_ThreadBlockSynchronization(node):
@@ -45,6 +46,7 @@ class CudaBackend(CBackend):
 
     def _print_TextureDeclaration(self, node):
 
+        # TODO: use fStrings here
         if node.texture.field.dtype.numpy_dtype.itemsize > 4:
             code = "texture<fp_tex_%s, cudaTextureType%iD, cudaReadModeElementType> %s;" % (
                 str(node.texture.field.dtype),
@@ -96,9 +98,13 @@ class CudaSympyPrinter(CustomSympyPrinter):
 
     def _print_Function(self, expr):
         if isinstance(expr, fast_division):
-            return "__fdividef(%s, %s)" % tuple(self._print(a) for a in expr.args)
+            assert len(expr.args) == 2, f"__fdividef has two arguments, but {len(expr.args)} where given"
+            return f"__fdividef({self._print(expr.args[0])}, {self._print(expr.args[1])})"
         elif isinstance(expr, fast_sqrt):
-            return f"__fsqrt_rn({tuple(self._print(a) for a in expr.args)})"
+            assert len(expr.args) == 1, f"__fsqrt_rn has one argument, but {len(expr.args)} where given"
+            return f"__fsqrt_rn({self._print(expr.args[0])})"
         elif isinstance(expr, fast_inv_sqrt):
-            return f"__frsqrt_rn({tuple(self._print(a) for a in expr.args)})"
+            print(len(expr.args) == 1)
+            assert len(expr.args) == 1, f"__frsqrt_rn has one argument, but {len(expr.args)} where given"
+            return f"__frsqrt_rn({self._print(expr.args[0])})"
         return super()._print_Function(expr)