Use correct C math.h functions for complex

[garth-wells]

For float, FFCx generates code that uses fabs but it should use fabsf for floats. Same is likely for other math functions.

Need to check and use correct functions.

[chrisrichardson]

I don't find it is wrong. I tried ffcx --scalar_type=float Poisson.py and it contains fabsf. Maybe it depends how it is called - from Python I guess it may not be passing scalar_type properly? Can you provide an example?

[garth-wells]

I don't find it is wrong. I tried ffcx --scalar_type=float Poisson.py and it contains fabsf. Maybe it depends how it is called - from Python I guess it may not be passing scalar_type properly? Can you provide an example?

I'll dig out the test that generated the compiler warnings.

[chrisrichardson]

I think I have found the problem here - not so much with float but with complex - the code generator assumes that all math functions should be appropriate for the scalar type (e.g. complex), but the geometry is never complex, so using e.g. cabs() is wrong, and generates a compiler warning. I think this could be fixed e.g. with a "typing" system for CNodes Symbol but that will require quite a bit of work.

[chrisrichardson]

Fixed in #594