Minggu, 23 Maret 2014
Pertemuan 04. E-Book Finding a Function Root Using the Bisection Method
#include <cstdlib>
#include <iostream>
#include <math.h>
#define FALSE 0
#define TRUE 1
#define NO_ROOT -99999.0
double bisect(double x_left,double x_right, double epsilon, double f( double farg));
double g(double x);
double h(double x);
using namespace std;
int main(void)
{
double x_left,x_right,epsilon,root;
cout<<"Enter interval endpoints> ";
cin>>x_left>>x_right;
cout<<"Enter tolerance> ";
cin>>epsilon;
cout<<"Function g"<<endl;
root = bisect(x_left,x_right,epsilon,g);
if(root != NO_ROOT)
cout<<"g ="<<root<<g(root)<<endl<<endl;
cout<<"Function h"<<endl;
root= bisect(x_left,x_right,epsilon,h);
if(root != NO_ROOT)
cout<<"h =n"<<root<<h(root);
return(0);
}
double bisect(double x_left, double x_right, double epsilon, double f(double farg))
{
double x_mid, f_left, f_mid, f_right;
int root_found;
f_left = f(x_left);
f_right = f(x_right);
if(f_left * f_right>0){
cout<<"May be no root in "<<x_left<<x_right<<endl;
return NO_ROOT;
}
root_found = FALSE;
while(fabs(x_right - x_left) > epsilon && !root_found)
{
x_mid = (x_left + x_right)/2.0;
f_mid = f(x_mid);
if(f_mid == 0.0){
root_found = TRUE;
}
else if (f_left * f_mid < 0.0) {
x_right = x_mid;
}
else {
x_left + x_mid;
}
if(root_found)
cout<<"Root found at x = ,midpoint of "<<x_mid<<x_right<<endl;
else
cout<<"New interval is "<<x_left<<x_right;
}
return ((x_left + x_right)/2.0);
}
double g(double x) {
return (5 * pow(x, 3.0) -2 *pow(x,2.0)+3);
}
double h(double x){
return(pow(x, 4.0) - 3 * pow(x,2.0) - 8);
};
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