NUmeric :Secant Method code

 

Sample equation for Secant Method

where X-1=3

and x0=4 ;

F(x)=2x³-11.7x²+17.7x¹-5

//scant method

#include<stdio.h>

#include<math.h>

#include<iostream>

using namespace std;

int main()

{

    float xi,Xii,newxi,Es,a[40],old=0,Ea;

    int n,K;

    cout<< "HIghest power in the equation : " ;

    cin>>n;

    //.........................................

    printf("Enter Xi =");

    scanf("%f",&xi);

    printf("Enter Xii =");

    scanf("%f",&Xii);

    printf("Enter Es =");

    scanf("%f",&Es);

    //..........................................

    printf("\n");

    printf("enter coefficient :\n");

    for (int i=n; i>=0; i--)

    {

        printf("X^%d =",i);

        scanf("%f",&a[i]);

    }

    //...........................................

    while(1)

    {

        float fxi=0,fXii=0;

//

       for (int i=n; i>=0; i--)

        {

             fxi=fxi+a[i]*pow(xi,i);

             fXii=fXii+a[i]*pow(Xii,i);

        }

        newxi=xi-((fxi*(Xii-xi))/(fXii-fxi));

//   printf("\n\n\nSTEP no: %d\n",K+1);

        printf("\nXi   =  %.2f",xi);

        printf("\nfxi  =  %.2f",fxi);

//

        printf("\nXii   =  %.2f",Xii);

        printf("\nfXii  =  %.2f",fXii);

//

        printf("\nnew Xi   =  %.2f",newxi);

//

        Ea=((newxi-old)/newxi)*100;

        old =newxi;

        //cout <<" now =" <<old;

        if(Ea<0)

        {

            Ea=Ea*(-1);

        }

        printf("\nEa= %f\n",Ea);

        if(Ea<Es)

        {

            break;

        }

        Xii=xi;

        xi=newxi;

        K++;

    }

    return 0;

}