GaussSeidel_v0.cpp
c7737fb94317master

GaussSeidel_v0.cpp
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			#include <iostream>
			#include <cmath>
			using namespace std;

			double* GaussSeidel(double A[5][5],double b[5]);


			int main() {
			double x[5];
			x[1]=1;
			x[2]=1;
			x[3]=1;
			x[4]=1;
			x[5]=1;
			double A[5][5];

			cout << "La matrice A vaut : " << endl;
			for(int i=0;i<5;++i) {
			for (int j = 0; j < 5; ++j) {
			if(i==j) {
			A[i][j]=25;
			cout << A[i][j] << " ";
			}else{
			A[i][j] = 0;
			cout << A[i][j] << " ";
			}

			}
			cout << endl;
			}
			cout << endl;

			double b[5];

			for(int j=0;j<5;++j)
			{
			b[j]=2;
			}
			double *solution;

			solution = GaussSeidel(A,b);
			cout << endl;
			cout << "La valeur de x est: " << endl;
			cout << solution[0] << endl;
			cout << solution[1] << endl;
			cout << solution[2] << endl;
			cout << solution[3] << endl;
			cout << solution[4] << endl;



			return 0;
			}

			double* GaussSeidel(double A[5][5],double b[5])
			{
			static double sol[5];

			double x[5];
			double xold[5];
			double e[5];
			double norm_e=1;
			for(int i=0;i<5;++i){
			x[i]=0;
			xold[i]=0;
			e[i]=1;
			}
			int count = 0;
			while(norm_e>1/100 && count<30) {

			for (int i = 0; i < 5; ++i) {
			x[i] = b[i] / A[i][i];
			for (int j = 0; j < 5; ++j) {
			if (i == j) {
			} else {
			x[i] = x[i] - (A[i][j] * x[j]) / A[i][i];
			}
			}
			if(xold[i]==0){
			e[i]=1;
			}else {
			e[i] = abs((x[i] - xold[i]) / xold[i]);
			}
			xold[i] = x[i];
			}
			norm_e=0;
			for(int i=0;i<5;++i){
			norm_e=norm_e + e[i]*e[i];
			}
			norm_e=sqrt(norm_e);

			count =count +1;
			}
			cout << "le nombre d'itérations du code est : " << endl;
			cout << count << endl;



			for(int i = 0;i<5;++i)
			{
			sol[i]=x[i];
			}


			return sol;
			}