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al_fixacos(3)                                                    al_fixacos(3)

NAME
       al_fixacos - Allegro 5 API

SYNOPSIS

              #include <allegro5/allegro.h>

              al_fixed al_fixacos(al_fixed x);

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

       Example:

                  al_fixed result;

                  /* Sets result to binary angle 128. */
                  result = al_fixacos(al_itofix(-1));

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 range.  All
       return values of this function will be in the range 0 to 128.

Allegro reference manual                                         al_fixacos(3)