fixasin

fixasin(3)                       Allegro manual                       fixasin(3)



NAME
       fixasin - Fixed point inverse sine lookup table. Allegro game programming
       library.

SYNOPSIS
       #include <allegro.h>


       fixed fixasin(fixed x);

DESCRIPTION
       This function finds the inverse sine of a value using a lookup table. The
       input value must be a fixed point value. The inverse sine is defined only
       in the domain from `-1' to `1'. Outside of this input range, the function
       will set `errno' to EDOM and return zero. Example:

          float angle;
          fixed val;

          /* Sets `val' to a right binary angle (`64'). */
          val = fixasin(itofix(1));
          /* Sets `angle' to 0.2405. */
          angle = fixtof(fixmul(fixasin(ftofix(0.238)), fixtorad_r));
          /* This will trigger the assert. */
          val = fixasin(ftofix(-1.09));
          ASSERT(!errno);

RETURN VALUE
       Returns the inverse sine of a fixed point value, measured as fixed point
       binary format angle, or zero if the input was out of the range. All
       return values of this function will be in the range `-64' to `64'.


SEE ALSO
Allegro                           version 4.4.3                       fixasin(3)