Provided by: allegro4-doc_4.4.2-13_all bug

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)