Coding Program Interpolasi Lagrange C++ - Metode Numerik

by VignettE on 9:03 PM in Kuliah, Pemograman

Disini saya akan membagikan koding program Interpolasi Lagrange Derajat 2 (3 Titik) yang telah saya edit sedikit untuk 4 inputan untuk X.

Contoh Data Tabel :

#include <stdio.h>

#include <iostream>

#include<conio.h>

using namespace std;

int main(void)

{

float xBar1,xBar2,xBar3,xBar4,hasil;

float x[100],f[100],l[100],hitung;

int n,i,j,k;

printf("\n\tMETODE LAGRANGE ");

printf("\n\tABDUL RHOFAR RIDHO - H1051131008 ");

printf("\n----------------------------------------------");

printf("\nMasukkan Jumlah Data : "); scanf("%i",&n);

printf("\n----------------------------------------------");

for(i=0;i<n;i++)

        {

        printf("\nMasukkan nilai x%i : ",i); scanf("%f",&x[i]);

        printf("Masukkan nilai y%i : ",i); scanf("%f",&f[i]);

        }

printf("\n----------------------------------------------");

printf("\nMasukkan nilai X1 : "); scanf("%f",&xBar1);

printf("\nMasukkan nilai X2 : "); scanf("%f",&xBar2);

printf("\nMasukkan nilai X3 : "); scanf("%f",&xBar3);

printf("\nMasukkan nilai X4 : "); scanf("%f",&xBar4);

printf("\n\n");

printf("Didapatkan titik X , Y adalah :\n ");

printf("\n");

for (i=0;i<n;i++)

        {

        cout <<"["<<x[i]<<"\t]\t["<<f[i]<<"\t]"<<endl;

        }



printf("dengan nilai X1 = %.2f ",xBar1);

hasil=(f[0]*((xBar1-x[1])/(x[0]-x[1]))*((xBar1-x[2])/(x[0]-x[2])))+(f[1]*((xBar1-x[0])/(x[1]-x[0]))*((xBar1-x[2])/(x[1]-x[2])))+(f[2]*((xBar1-x[0])/(x[2]-x[0]))*((xBar1-x[1])/(x[2]-x[1])));

printf("\nMaka nilai Y untuk X yang dicari : %.3f",xBar1);

printf("\tadalah : %.3f",hasil);

printf("\n\ndengan nilai X2 = %.2f ",xBar2);

hasil=(f[0]*((xBar2-x[1])/(x[0]-x[1]))*((xBar2-x[2])/(x[0]-x[2])))+(f[1]*((xBar2-x[0])/(x[1]-x[0]))*((xBar2-x[2])/(x[1]-x[2])))+(f[2]*((xBar2-x[0])/(x[2]-x[0]))*((xBar2-x[1])/(x[2]-x[1])));

printf("\nMaka nilai Y untuk X yang dicari : %.3f",xBar2);

printf("\tadalah : %.3f",hasil);

printf("\n\ndengan nilai X3 = %.2f ",xBar3);

hasil=(f[0]*((xBar3-x[1])/(x[0]-x[1]))*((xBar3-x[2])/(x[0]-x[2])))+(f[1]*((xBar3-x[0])/(x[1]-x[0]))*((xBar3-x[2])/(x[1]-x[2])))+(f[2]*((xBar3-x[0])/(x[2]-x[0]))*((xBar3-x[1])/(x[2]-x[1])));

printf("\nMaka nilai Y untuk X yang dicari : %.3f",xBar3);

printf("\tadalah : %.3f",hasil);

printf("\n\ndengan nilai X4 = %.2f ",xBar4);

hasil=(f[0]*((xBar4-x[1])/(x[0]-x[1]))*((xBar4-x[2])/(x[0]-x[2])))+(f[1]*((xBar4-x[0])/(x[1]-x[0]))*((xBar4-x[2])/(x[1]-x[2])))+(f[2]*((xBar4-x[0])/(x[2]-x[0]))*((xBar4-x[1])/(x[2]-x[1])));

printf("\nMaka nilai Y untuk X yang dicari : %.3f",xBar4);

printf("\tadalah : %.3f",hasil);

getch();

return(0);

}