al_fixacos
al_fixed al_fixacos(al_fixed x);
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.