/*************************    Program 2.6    ****************************/
/*                                                                      */
/************************************************************************/
/* Please Note:                                                         */
/*                                                                      */
/* (1) This computer program is written by Tao Pang in conjunction with */
/*     his book, "An Introduction to Computational Physics," published  */
/*     by Cambridge University Press in 1997.                           */
/*                                                                      */
/* (2) No warranties, express or implied, are made for this program.    */
/*                                                                      */
/************************************************************************/

#include <stdio.h>
#include <math.h>
#define f(x) (exp(x)*log(x)-x*x)

main()
/* This program uses the bisection method to find the root of
   f(x)=exp(x)*ln(x)-x*x=0.  Copyright (c) Tao Pang 1997. */
{
int istep;
double dl=1e-6;
double a,b,x0,x1,dx;

a = 1; b = 2;
dx = b-a;
istep = 0;
while (fabs(dx) > dl)
  {
  x0 = (a+b)/2;
  if ((f(a)*f(x0)) < 0)
    {
    b  = x0;
    dx = b-a;
    }
  else
     {
     a  = x0;
     dx = b-a;
     }
  istep = istep+1;
  }
printf("%4d %16.8lf %16.8lf\n", istep,x0,dx);
}