cos.c

#include "lib/math.h"
 
double cos(double rads) {
    size_t steps = 16;
    double result = 1.0;
 
    bool flag = false;
 
    for (size_t i = 2; i < steps + 1; i += 2)
    {
        if (!flag)
        {
            result -= pow(rads, i) / fac(i);
        }
        else
        {
            result += pow(rads, i) / fac(i);
        }
        flag = !flag;
    }
 
    return result;
}