Print double literals always with .

pystencils/backends/cbackend.py

@@ -378,6 +378,9 @@ class CustomSympyPrinter(CCodePrinter):
                     res += ".0f"
                 else:
                     res += "f"
+            else:
+                if '.' not in res:
+                    res += "."
             return res
         else:
             return res