# Numerical Methods: Inverse of nxn matrix using C

Source Code:

#include<stdio.h>
int main(){
float matrix, ratio,a;
int i, j, k, n;
printf("Enter order of matrix: ");
scanf("%d", &n);
printf("Enter the matrix: \n");
for(i = 0; i < n; i++){
for(j = 0; j < n; j++){
scanf("%f", &matrix[i][j]);
}
}
for(i = 0; i < n; i++){
for(j = n; j < 2*n; j++){
if(i==(j-n))
matrix[i][j] = 1.0;
else
matrix[i][j] = 0.0;
}
}
for(i = 0; i < n; i++){
for(j = 0; j < n; j++){
if(i!=j){
ratio = matrix[j][i]/matrix[i][i];
for(k = 0; k < 2*n; k++){
matrix[j][k] -= ratio * matrix[i][k];
}
}
}
}
for(i = 0; i < n; i++){
a = matrix[i][i];
for(j = 0; j < 2*n; j++){
matrix[i][j] /= a;
}
}
printf("The inverse matrix is: \n");
for(i = 0; i < n; i++){
for(j = n; j < 2*n; j++){
printf("%.2f", matrix[i][j]);
printf("\t");
}
printf("\n");
}
return 0;
}


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### 17 Responses

1. Awat Marouf ( اوات معروف ) says:

it is very useful program with nice style

2. Anonymous says:

Guy you mix I/O with business logic.

3. Anonymous says:

Nice and useful code. Thank you.

4. Anonymous says:

what when matrix[i][i]=0. You have not taken care of such situation. When u are going to deal with n*2n matrix, why create a matrix of size 10*10. You should have created a matrix of 5*10 or 10*20 or …

5. MH Raihan says:

I just want to ask this type similar question . Did you solve if matrix = 0; ?

6. Anonymous says:

How amazing work. You help me out. Thanks very much.

7. ABDUL GHANI says:

Is this code work properly with a 6×6 matrix of complex numbers?

8. This And That says:

for solving divide by 0 when matrix == 0 use pivoting
example
http://ganeshtiwaridotcomdotnp.blogspot.in/2009/12/c-c-code-gauss-jordan-method-for.html

9. Bits Bots says:

Thanks.

10. Anonymous says:

you must check if the matrix is invertible or not by calculating the determinant of the matrix ,that is,if the determinant is zero ,the matrix has no inverse

11. Anonymous says:

values getting replaced…..so no problem if 0 present as diagonal element

12. Anonymous says:

inverse of such a matrix will never exist

13. Unknown says:

??

14. Grace says:

what approach did u use? I don't completely understand your program.

15. Anonymous says:

is this code working when i runthiscode it is giving nan

16. sakshi says:

logic seems incorrect as matrix[i][i] is 0.
doesnt work for huge matrix.

17. Anonymous says:

Very smooth code, saved me a lot of work 🙂 