linux man page for fixatan2

fixatan2(3alleg4)						  Allegro manual						 fixatan2(3alleg4)

NAME
       fixatan2 - Fixed point version of the libc atan2() routine. Allegro game programming library.

SYNOPSIS
       #include <allegro.h>

       fixed fixatan2(fixed y, fixed x);

DESCRIPTION
       This is a fixed point version of the libc atan2() routine. It computes the arc tangent of `y / x', but the signs of both arguments are used
       to determine the quadrant of the result, and `x' is permitted to be zero. This function is useful to convert Cartesian coordinates to polar
       coordinates.  Example:

	  fixed result;

	  /* Sets `result' to binary angle 64. */
	  result = fixatan2(itofix(1), 0);
	  /* Sets `result' to binary angle -109. */
	  result = fixatan2(itofix(-1), itofix(-2));
	  /* Fails the assert. */
	  result = fixatan2(0, 0);
	  ASSERT(!errno);

RETURN VALUE
       Returns the arc tangent of `y / x' in fixed point binary format angle, from `-128' to `128'. If both `x' and `y' are zero, returns zero and
       sets `errno' to EDOM.

SEE ALSO
       , exlights(3alleg4), exspline(3alleg4)

Allegro 							   version 4.4.2						 fixatan2(3alleg4)