Trig_Blog_Sample_6

#include <math.h>
#include <cstdio>
#define _USE_MATH_DEFINES


struct point
{
    float x_pos;
    float y_pos;
    float _Hypot;
    float _Asin;
    float _Asin_Mod;
};


int main()
{
    point a_point[4];


    a_point[0].x_pos = 300.0f;
    a_point[0].y_pos = 200.0f;
    a_point[1].x_pos = -200.0f;
    a_point[1].y_pos = 300.0f;
    a_point[2].x_pos = -300.0f;
    a_point[2].y_pos = -200.0f;
    a_point[3].x_pos = 200.0f;
    a_point[3].y_pos = -300.0f;


    int i;
    for( i = 0; i < 4; i++)
    {
        a_point[i]._Hypot = hypotf(a_point[i].y_pos, a_point[i].x_pos);
        a_point[i]._Asin = asinf(a_point[i].y_pos / a_point[i]._Hypot);


        // Here's the quadrant correction...
        if(a_point[i].x_pos >= 0.0f && a_point[i].y_pos >= 0.0f)
        {
            a_point[i]._Asin_Mod = asinf(a_point[i].y_pos / a_point[i]._Hypot);
        }
        if(a_point[i].x_pos < 0.0f && a_point[i].y_pos >= 0.0f)
        {
            a_point[i]._Asin_Mod = M_PI - asinf(a_point[i].y_pos / a_point[i]._Hypot);
        }
        if(a_point[i].x_pos < 0.0f && a_point[i].y_pos < 0.0f)
        {
            a_point[i]._Asin_Mod = M_PI + (asinf(a_point[i].y_pos / a_point[i]._Hypot) * -1);
        }
        if(a_point[i].x_pos >= 0.0f && a_point[i].y_pos < 0.0f)
        {
            a_point[i]._Asin_Mod = asinf(a_point[i].y_pos / a_point[i]._Hypot) + (M_PI * 2.0f);
        }


        printf("\nPOINT %d\n", i);
        printf("X Pos: %.1f\nY Pos: %.1f\nAsin : %.3f\nAsinMod: %.3f\n\n",
            a_point[i].x_pos, a_point[i].y_pos, a_point[i]._Asin, a_point[i]._Asin_Mod);
    }
    return 0;
}