#include <stdio.h>
    #include <math.h>
    main() {
      float a, b, c, x1, x2;
      float r, s;
      a = 2.0; b = 3.0; c = 4.0;
      r = b * b - 4.0 * a * c;
      if( r > 0.0 )
        {
          s = sqrt(r);
          x1 = (-b + s) / (2.0 * a);
          x2 = (-b - s) / (2.0 * a);
          printf("real: x1 =%15.7f, x2 =%15.7f\n",x1,x2);
        }
      else if( r == 0.0 )
          printf("double: x1, x2 =%15.7f\n",-b/(2.0*a));
      else
       {
          x1 = -b / (2.0 * a);
          x2 = sqrt(-r) / (2.0 * a);
          printf("complex: Re=%15.7f, Im=%15.7f\n",x1,x2);
       }
       while(1);
    }