fast approximate algorithm of phase for complex number
I am using dsPIC33CK64MP506 MCU, XC16 compiler v1.41.
I want to get feature data of a fractcomplex-type data, which are its magnitude and phase.
I found build-in functions "_Q15sqrt"&"_Q15atanYByX" in <libq.h>, but it turns out "_Q15atanYByX" takes too much time to get the result for me(well _Q15sqrt is ok). Does anyone can share some fast approximate algorithms of phase estimation? (Given the actual phase range is [-45°, 45°])， THX in advance!