gauss.cpp

#include<iostream>
#include<cmath>
#include<cstdlib>
#define N 10
#define E 0.001

using namespace std;

double getRand(){
    int sign;
    if( (rand() % 10) < 5){
        sign = 1;
    }else{
        sign = -1;
    }
    //cout << rand() % 10 * sign << "\n";
    return static_cast <double> (rand()) / static_cast <double> (RAND_MAX);
    //return rand() % 10;
}

double getSum(double arr[]){
    double sum=0;
    for(long i=0;i<N;i++){
        sum+=arr[i];
    }
    return sum;
}


void printMatrix(double arr[N][N]){
    long i=0, j=0;
    cout <<  "======\n" ;
    for(i=0;i<N;i++) {
        for(j=0;j<N;j++) {
            cout << arr[i][j] <<  " ";
        }
        cout << "\n";
    }
    cout <<  "======\n ";
}

int main() {
    long i,j,m,n,l;
    static double x[N],a[N][N],b[N],c;
    double nU, nD, first;

    srand((unsigned) time(NULL));

    for(i=0;i<N;i++) {
        b[i] = getRand();
    }

    for(i=0;i<N;i++) {
        x[i]=0;
        for(j=0;j<N;j++) {
            a[i][j] = getRand();
        }
    }

    for(i=0;i<N;i++) {
        a[i][i] = getSum(a[i]) + getRand() + 1;
    }
    printMatrix(a);

    while(true){
        nU = nD = 0;
        for(i=0;i<N;i++) {
            c=b[i];
            for(j=0;j<N;j++) {
                if(i!=j) {
                    c-=a[i][j]*x[j];
                }
            }
            x[i]=c/a[i][i];
            nU += fabs(c) * fabs(c);
            nD += fabs(b[i]) * fabs(b[i]);
        }
        if (sqrt(nU) / sqrt(nD) < E){
            break;
        }
    }

    cout<<"\n===== answer: \n";
    for(i=0;i<N;i++) {
        cout<<"\nx("<<i<<") = "<<x[i]<<"\n";
    }
}

jacobi.cpp

#include<iostream>
#include<cmath>
#include<cstdlib>
#define N 300
#define E 0.001

using namespace std;

float getRand(){
    int sign;
    if( (rand() % 10) < 5){
        sign = 1;
    }else{
        sign = -1;
    }
    return static_cast <float> (rand()) / static_cast <float> (RAND_MAX);
}

float getSum(float arr[]){
    float sum=0;
    for(long i=0;i<N;i++){
        sum+=arr[i];
    }
    return sum;
}


void printMatrix(float arr[N][N]){
    long i=0, j=0;
    cout <<  "======\n" ;
    for(i=0;i<N;i++) {
        for(j=0;j<N;j++) {
            cout << arr[i][j] <<  " ";
        }
        cout << "\n";
    }
    cout <<  "======\n ";
}

int main() {
    long i,j,m,n,l;
    static float xNew[N], xOld[N], a[N][N], b[N], c;
    double nU, nD, first;

    srand((unsigned) time(NULL));

    for(i=0;i<N;i++) {
        b[i] = getRand();
    }
    for(i=0;i<N;i++) {
        xOld[i]=0;
        for(j=0;j<N;j++) {
            a[i][j] = getRand();
        }
    }

    for(i=0;i<N;i++) {
        a[i][i] = getSum(a[i]) + getRand() + 1;
    }

    while(true){
        nU = nD = 0;
        for(i=0;i<N;i++) {
            c=b[i];
            for(j=0;j<N;j++) {
                if(i!=j) {
                    c-=a[i][j]*xOld[j];
                }
            }
            xNew[i]=c/a[i][i];
            xOld[i] = xNew[i];
            
            nU += fabs(c) * fabs(c);
            nD += fabs(b[i]) * fabs(b[i]);
        }

        if (sqrt(nU) / sqrt(nD) < E){
            break;
        }
    }

    cout<<"\n===== answer: \n";
    for(i=0;i<N;i++) {
        cout<<"\nx("<<i<<") = "<<xNew[i]<<"\n";
    }
}