All Programs are Written and Compiled in Dev C++. So, it may generate some error in case of other compilers and may need some modifications in program. Download Dev C++

Tuesday 17 March 2015

Soving System of Linear Eq. By LU Factorization Method

#include<iostream>
using namespace std;
int main()
{
    int i,j,k,n,p;
    float a[10][10],l[10][10]={0},u[10][10]={0},b[10],z[10]={0},x[10]={0};
    cout<<"Enter order of matrix: ";
    cin>>n;
    cout<<"Enter the coefficients of matrix A\n";
    for(i=1;i<=n;i++)
    {
        for(j=1;j<=n;j++)
            cin>>a[i][j];
    }

    cout<<"Enter Elements of Matrix B\n";
    for(i=1;i<=n;i++)
        cin>>b[i];
    float sum=0.0;
    for(k=1;k<=n;k++)
    {
        u[k][k]=1;
        for(i=k;i<=n;i++)
        {
            sum=0;
            for(p=1;p<=k-1;p++)
                sum+=l[i][p]*u[p][k];
            l[i][k]=a[i][k]-sum;
        }
        for(j=k+1;j<=n;j++)
        {
            sum=0;
            for(p=1;p<=k-1;p++)
                sum+=l[k][p]*u[p][j];
            u[k][j]=(a[k][j]-sum)/l[k][k];
        }
    }
    cout<<"\nMatrix L & U\n";
    for(i=1;i<=n;i++)
    {
        for(j=1;j<=n;j++)
            cout<<l[i][j]<<"   ";
        cout<<endl;
    }
    cout<<endl;
    for(i=1;i<=n;i++)
    {
        for(j=1;j<=n;j++)
            cout<<u[i][j]<<"   ";
        cout<<endl;
    }
    //Forward Substitution LZ=b
    for(i=1;i<=n;i++)
    {
        sum=0;
        for(p=1;p<i;p++)
            sum+=l[i][p]*z[p];
        z[i]=(b[i]-sum)/l[i][i];
    }
    //Finding X ; UX=Z
    for(i=n;i>0;i--)
    {
        sum=0;
        for(p=n;p>i;p--)
            sum+=u[i][p]*x[p];
        x[i]=(z[i]-sum)/u[i][i];
    }
    //Printing solution
    for(i=1;i<=n;i++)
        cout<<"\nX"<<i<<"= "<<x[i];
    0;
}
return

No comments:

Post a Comment