NUmeric : Newton Rapson code

 

Sample equation for Newton Rapson

where X=3;

F(x)=2x³-11.7x²+17.7x¹-5

 

//NETON RAPSON

#include<stdio.h>

#include<math.h>

#include<iostream>

using namespace std;

int main()

{

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

    int n,K=0;

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

    cin>>n;

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

    printf("Enter Xi =");

    scanf("%f",&xi);

    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,deff=0;

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

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

        {

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

        }

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

        {

            deff=deff+i*a[i]*pow(xi,i-1);

        }

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

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

        printf("\ndeff   =  %.2f",deff);

        xiii=(xi-(fxi/deff));

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

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

        if(Ea<0)

        {

            Ea=Ea*(-1);

        }

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

            old=xiii;

            if(Ea<Es)

        {

            break;

        }

        xi=xiii;

        K++;

    }

    return 0;

}