sin&cos.c

#include <stdio.h>

#define PI 3.1415926535898
#define sqrt2 1.41421356237


double fabs(double input){
    return input > 0 ? input : (-input);
}

double get(double sinVal, double cosVal){
    int correct;
    int coefficient;
    if (cosVal > 0 && sinVal > 0){
        correct = 0;
        coefficient = 1;
    }
    else if (cosVal < 0 && sinVal > 0){
        correct = 180;
        coefficient = -1;
    }
    else if (cosVal < 0 && sinVal < 0){
        correct = 180;
        coefficient = 1;
    }
    else if (cosVal > 0 && sinVal < 0){
        correct = 0;
        coefficient = -1;
    }
    sinVal = fabs(sinVal);
    cosVal = fabs(cosVal);
    int i, j;
    double prev, diff;
    const double sinK[5] = {0.0173648177667, 0.0168371965659,
                            0.0157979856674, 0.0142787609687,
                            0.0123256833432};
    const double sinB[5] = {0.0, 0.00527621200819, 0.026060429977,
                            0.0716371709404, 0.149760275957};
    const double sinSep[6] = {0, 0.174522183226460, 0.342020143325669,
                           0.5, 0.642787609686539, 0.766044443118978};

    const double cosK[5] = {-0.0142787609687, -0.0157979856674,
                            -0.0168371965659, -0.0173648177667,
                            -0.0173648177667};
    const double cosB[5] = {1.35672565812, 1.44787914005, 1.52062390294,
                            1.562833599, 1.562833599};
    const double cosSep[6] = {0.642787609687, 0.5, 0.342020143326,
                              0.173648177667, 6.12323399574e-17, 0};

    for (i=0;i<5;i++)
        if (sinSep[i] <= sinVal && sinVal < sinSep[i+1])
            return coefficient * ((sinVal - sinB[i]) / sinK[i]) + correct;

    for (i=0;i<5;i++)
        if (cosSep[i+1] < cosVal && cosVal <= cosSep[i])
            return coefficient * ((cosVal - cosB[i]) / cosK[i]) + correct;

    return -1;
}


int main(){
    double s;
    double c;
    scanf("%lf", &s);
    scanf("%lf", &c);
    printf("%lf", get(s, c));
    return 0;
}