Matrix Inverse Using Gauss Jordan Method C++ Program with Output

Complete C++ Program for inversing given square matrix using Gauss Jordan method with output.

C++ Program for Matrix Inverse using Gauss Jordan

	
#include<iostream>
#include<iomanip>
#include<math.h>
#include<stdlib.h>

#define SIZE 10

using namespace std;

int main()
{
		 float a[SIZE][SIZE], x[SIZE], ratio;
		 int i,j,k,n;

         /* Setting precision and writing floating point values in fixed-point notation. */
         cout<< setprecision(3)<< fixed;

		 /* Inputs */
		 /* 1. Reading order of matrix */
		 cout<<"Enter order of matrix: ";
		 cin>>n;

		 /* 2. Reading Matrix */
		 cout<<"Enter coefficients of Matrix: " << endl;
		 for(i=1;i<=n;i++)
		 {
			  for(j=1;j<=n;j++)
			  {
				   cout<<"a["<< i<<"]"<< j<<"]= ";
                   cin>>a[i][j];
			  }
		 }

		 /* Augmenting Identity Matrix of Order n */
		 for(i=1;i<=n;i++)
		 {
			  for(j=1;j<=n;j++)
			  {
				   if(i==j)
				   {
				    	a[i][j+n] = 1;
				   }
				   else
				   {
				    	a[i][j+n] = 0;
				   }
			  }
		 }

		 /* Applying Gauss Jordan Elimination */
		 for(i=1;i<=n;i++)
		 {
			  if(a[i][i] == 0.0)
			  {
				   cout<<"Mathematical Error!";
				   exit(0);
			  }
			  for(j=1;j<=n;j++)
			  {
				   if(i!=j)
				   {
					    ratio = a[j][i]/a[i][i];
					    for(k=1;k<=2*n;k++)
					    {
					     	a[j][k] = a[j][k] - ratio*a[i][k];
					    }
				   }
			  }
		 }
		 /* Row Operation to Make Principal Diagonal to 1 */
		 for(i=1;i<=n;i++)
		 {
			  for(j=n+1;j<=2*n;j++)
			  {
			   	a[i][j] = a[i][j]/a[i][i];
			  }
		 }
		 /* Displaying Inverse Matrix */
		 cout<< endl<<"Inverse Matrix is:"<< endl;
		 for(i=1;i<=n;i++)
		 {
			  for(j=n+1;j<=2*n;j++)
			  {
			   	cout<< a[i][j]<<"\t";
			  }
			  cout<< endl;
		 }
		 return(0);
}

	

Output

Enter order of matrix: 3
Enter coefficients of Matrix:
a[1]1]= 1
a[1]2]= 1
a[1]3]= 3
a[2]1]= 1
a[2]2]= 3
a[2]3]= -3
a[3]1]= -2
a[3]2]= -4
a[3]3]= -4

Inverse Matrix is:
3.000   1.000   1.500
-1.250  -0.250  -0.750
-0.250  -0.250  -0.250

Recommended Readings

1. Matrix Inverse Using Gauss Jordan Method Algorithm
2. Matrix Inverse Using Gauss Jordan Method Pseudocode
3. Matrix Inverse Using Gauss Jordan C Program
4. Matrix Inverse Using Gauss Jordan C++ Program