Clarify types in atan2() call for usage in MSVC++.
Clarify types in atan2() call for usage in MSVC++.

cython/cython,da-woods/cython,da-woods/cython,scoder/cython,cython/cython,cython/cython,da-woods/cython,cython/cython,da-woods/cython,scoder/cython,scoder/cython,scoder/cython