#include <assert.h>
#include <math.h>

double weibullDF(double x, double b, double c)
{
   assert((b > 0) && (c > 0));
   double y = 1-exp(-pow(x/b,c));
   return y;
}

double inv_weibullDF(double q, double b, double c)
{
   assert((b > 0) && (c > 0) && (q >= 0) && (q < 1));
   return q==0 ? 0 : b*pow(-log(1-q),1/c);
}

#ifdef TEST

#include <iostream.h>

void main(void)
{
   double b, c;

   while (1) {
      cout << "\n\n\rEnter b: ";
      cin >> b;
      if (b <= 0)
	 break;
      cout << "Enter c: ";
      cin >> c;

      for(double x=0; x < 8; x += 0.32)
      {
         double y=weibullDF(x, b, c);
         cout << "x=" << x << "\tw=" << y;
         double z=inv_weibullDF(y, b, c);
         cout << "\tiw=" << z << endl;
      }
   }
}

#endif