/Users/yzchen/ns/ns-allinone-2.33/ns-2.33/tcp/formula-with-inverse.h

#include "formula.h"

double b_to_p(double b, double rtt, double tzero, int psize, int bval) 
{
        double p, pi, bres;
        int ctr=0;
        p=0.5;pi=0.25;
        while(1) {
                bres=p_to_b(p,rtt,tzero,psize, bval);
                /*
                 * if we're within 5% of the correct value from below, this is OK
                 * for this purpose.
                 */
                if ((bres>0.95*b)&&(bres<1.05*b)) 
                        return p;
                if (bres>b) {
                        p+=pi;
                } else {
                        p-=pi;
                }
                pi/=2.0;
                ctr++;
                if (ctr>30) {
                        return p;
                }
        }
}