计算一元二次方程的解

 1 #include<stdio.h>
 2 #include<math.h>
 3 int main()
 4 {
 5     double a,b,c,disc,x1,x2,realpart,imagpart;
 6     scanf("%lf,%lf,%lf",&a,&b,&c);
 7     printf("the eauation ");
 8     if(fabs(a)<=1e-6)
 9         printf("is not a quadratic
");
10     else
11     {
12         disc=b*b-4*a*c;
13         if(fabs(disc)<=1e-6)
14             printf("has tow eaual roots:%8.4f
",-b/(2*a));
15         else
16             if(disc>=1e-6)
17             {
18                 x1=(-b+sqrt(disc))/(2*a);
19                 x2=(-b-sqrt(disc))/(2*a);
20                 printf("has distinct real roots:%8.4f and %8.4F
",x1,x2);
21             }
22             else
23             {
24                 realpart=-b/(2*a);
25                 imagpart=sqrt(disc)/(2*a);
26                 printf("has complex roots:
");
27                 printf("%8.4f+%8.4f i
",realpart,imagpart);
28                 printf("%8.4f-%8.4f i
",realpart,imagpart);
29             }
30     }return 0;
31 }