al_fixed al_fixacos(al_fixed x);
Introduced in 5.0.0

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.


    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.