Equation Set

assignment-1.c

#include <stdio.h>
/* Question:
** write a program to solve equation set 
** ax + by = 1
** cx + dy = 2
** and print the result
*/

int main(void)
{
    double a,b,c,d,e,x,y;
    printf("enter the a,b,c,d in fomula\na: ");
    scanf("%lf",&a);
    printf("b: ");
    scanf("%lf",&b);
    printf("c: ");
    scanf("%lf",&c);
    printf("d: ");
    scanf("%lf",&d);

    e=a*d-b*c;
    x=(d-2.0*b)/e;
    y=(2.0*a-c)/e;

    if(a/c==b/d)
    {
        if(a/c==0.5) /* it should be 0.5 rather than 1/2, because a/c is float */
        {
            printf("infinite answer");
        } 
        else
        {
            printf("no answer");
        }
    }
    else
    {
        printf("x,y=%f,%f",x,y);
    }
    return 0;
}