#include <iostream>
#include <fstream>
#include <cmath>
#include <iomanip>
#include "testfun.h"

using namespace std;

void fixpoint(double xstart, int nmax, double &xnew, double &errfun)
{
	ofstream oconv("conv");
	oconv.precision(10);
	oconv<<fixed<<scientific;
	double fnew;
	double xold = xstart;
	double fold = FF(xold);
	oconv<<"0  "<<xold<<"  "<<fabs(fold-xold)<<endl;
//
//___ start iterating _______________
//
	cout.precision(10);
	cout<<fixed<<scientific;
	bool maxIter = false;
	for(int niter=1;niter<=nmax;niter++)
	{
		xnew = fold;
		fnew = FF(xnew);
		cout <<niter<<"  "<<xnew<<"  "<<fabs(xnew-fnew)<<endl;
		oconv<<niter<<"  "<<xnew<<"  "<<fabs(xnew-fnew)<<endl;
//-- Is XR a root?
		if(fabs(xnew-fnew) < errfun) 
		{
			errfun = fabs(xnew-fnew);
			maxIter = false;
			break;
		}
//-- update
		xold = xnew;
		fold = fnew;
		maxIter = true;
	}
	if(maxIter)
		cout<<"Non-coverged"<<endl;
	oconv.close();	
	
	return ;
}