From 0178dcc25f04d5a796e2ce9f89f08088b87d986d Mon Sep 17 00:00:00 2001
From: Martin Bauer <martin.bauer@fau.de>
Date: Fri, 6 Jul 2018 11:13:51 +0200
Subject: [PATCH] CBackend: support for negative integer exponentials
---
backends/cbackend.py | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/backends/cbackend.py b/backends/cbackend.py
index 9becd107d..e5d9730ff 100644
--- a/backends/cbackend.py
+++ b/backends/cbackend.py
@@ -220,6 +220,8 @@ class CustomSympyPrinter(CCodePrinter):
"""Don't use std::pow function, for small integer exponents, write as multiplication"""
if expr.exp.is_integer and expr.exp.is_number and 0 < expr.exp < 8:
return "(" + self._print(sp.Mul(*[expr.base] * expr.exp, evaluate=False)) + ")"
+ elif expr.exp.is_integer and expr.exp.is_number and - 8 < expr.exp < 0:
+ return "1 / ({})".format(self._print(sp.Mul(*[expr.base] * (-expr.exp), evaluate=False)))
else:
return super(CustomSympyPrinter, self)._print_Pow(expr)
@@ -359,14 +361,17 @@ class VectorizedCustomSympyPrinter(CustomSympyPrinter):
if expr.exp.is_integer and expr.exp.is_number and 0 < expr.exp < 8:
return "(" + self._print(sp.Mul(*[expr.base] * expr.exp, evaluate=False)) + ")"
+ elif expr.exp == -1:
+ one = self.instruction_set['makeVec'].format(1.0)
+ return self.instruction_set['/'].format(one, self._print(expr.base))
+ elif expr.exp == 0.5:
+ return self.instruction_set['sqrt'].format(self._print(expr.base))
+ elif expr.exp.is_integer and expr.exp.is_number and - 8 < expr.exp < 0:
+ one = self.instruction_set['makeVec'].format(1.0)
+ return self.instruction_set['/'].format(one,
+ self._print(sp.Mul(*[expr.base] * (-expr.exp), evaluate=False)))
else:
- if expr.exp == -1:
- one = self.instruction_set['makeVec'].format(1.0)
- return self.instruction_set['/'].format(one, self._print(expr.base))
- elif expr.exp == 0.5:
- return self.instruction_set['sqrt'].format(self._print(expr.base))
- else:
- raise ValueError("Generic exponential not supported")
+ raise ValueError("Generic exponential not supported: " + str(expr))
def _print_Mul(self, expr, inside_add=False):
# noinspection PyProtectedMember
--
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