Cartesian to angle

[Ether]

atan2(x,y) gives +/-pi clockwise from the +Y axis. That puts the discontinuity on the -Y axis, which then requires you to add conditional logic to fix it. There's a better way.


BTW, concerning atan2(0,0), many modern implementations, such as the microcode in the FP unit of the Pentium*, helpfully return zero when both arguments are zero. Does anyone know what the FRC versions of LabVIEW, C++, and Java do?


* here's a short test code written in Delphi:

USES windows, sysutils;


Function FPatan2(y : extended; x : extended): Extended;
Assembler;
asm fld [y] ; fld [x] ; fpatan end ;


BEGIN

write(FPatan2(0,0),' Pentium FP processor built-in microcode');

END.