Simplify constant square roots

pystencils/backends/cbackend.py

@@ -299,6 +299,9 @@ class CustomSympyPrinter(CCodePrinter):
 
     def _print_Pow(self, expr):
         """Don't use std::pow function, for small integer exponents, write as multiplication"""
+        if not expr.free_symbols:
+            return self._typed_number(expr.evalf(), get_type_of_expression(expr))
+
         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:

pystencils/data_types.py

@@ -70,6 +70,9 @@ class cast_func(sp.Function):
     def is_commutative(self):
         return self.args[0].is_commutative
 
+    def _eval_evalf(self, *args, **kwargs):
+        return self.args[0].evalf()
+
     @property
     def dtype(self):
         return self.args[1]