HW2ex3

#include <math.h>
#include <stdio.h>
#include <stdlib.h>

double calculate(double* a, double* b, double* c, double* x1, double* x2) {

    //ax2 + bx = c
    //D = b2 - 4*a*c
    //x1 = -b + sqrt(D) / 2
    //x2 = -b - sqrt(D) / 2

    double D;
    D = *b * *b - 4 * *a * *c;
    if(D > 0) {
        *x1 = ((-1) * *b + sqrt(D)) / 2;
        *x2 = ((-1) * *b - sqrt(D)) / 2;
        return 0;
    } else if(D < 0) {
        return 2;
    } else {
        *x1 = ((-1) * *b + sqrt(D)) / 2;
        *x2 = *x1;
        return 0;
    }


}

int main(int args, char *argv[]) {
    double a, b, c;
    double x1, x2;

    a = atof(argv[1]);
    b = atof(argv[2]);
    c = atof(argv[3]);

    if(calculate(&a, &b, &c, &x1, &x2) == 0) {
        printf("x1: %lf\n", x1);
        printf("x2: %lf\n", x2);
    } else {
        fprintf(stderr, "No real roots\n");
    }

    return 0;

}