Matrix Inverse Using Gauss Jordan Method C Program


Earlier in Matrix Inverse Using Gauss Jordan Method Algorithm and Matrix Inverse Using Gauss Jordan Method Pseudocode , we discussed about an algorithm and pseudocode for finding inverse of matrix using Gauss Jordan Method. In this tutorial we are going to implement this method using C programming language.

Complete C Program for Matrix Inversion Using Gauss Jordan Method


#include<stdio.h>
#include<conio.h>
#include<math.h>

#define SIZE 10

int main()
{
		 float a[SIZE][SIZE], x[SIZE], ratio;
		 int i,j,k,n;
		 clrscr();
		 /* Inputs */
		 /* 1. Reading order of matrix */
		 printf("Enter order of matrix: ");
		 scanf("%d", &n);
		 /* 2. Reading Matrix */
		 printf("Enter coefficients of Matrix:\n");
		 for(i=1;i<=n;i++)
		 {
			  for(j=1;j<=n;j++)
			  {
				   printf("a[%d][%d] = ",i,j);
				   scanf("%f", &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)
			  {
				   printf("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 */
		 printf("\nInverse Matrix is:\n");
		 for(i=1;i<=n;i++)
		 {
			  for(j=n+1;j<=2*n;j++)
			  {
			   	printf("%0.3f\t",a[i][j]);
			  }
			  printf("\n");
		 }
		 getch();
		 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