Thread: Matrix inversion

I have looked up matrix inversions for the past two days and still cannot properly code a program that can compute the inverse of any square matrix. I found code online that works, but only if the first numbers in each row are 1. For any other numbers, the calculation is almost correct. The only difference between the code I found and the correct results is the multiplication of each element in every row after the first by some constant.

The code I have thus far:

Code:

#include<stdio.h>
#include<stdlib.h>


int main(void)
{
    int n=3;
    double A[3][3]= {{1,-1,3},{2,1,2},{-2,-2,1}};
    double B[n][2*n];
    int i,j,k;
    double M;

 

    /*-------------Create Matrix w/identity---------------*/


    for( i=0;i<n;i++)
    {
        for( j=n;j<2*n;j++)
        {
            if(j==(i+n))
		{
                B[i][j]=1.0;
                }

            else
            {
                B[i][j]=0.0;
            }
        }
    }


	
	for(i=0; i<n; i++) 
		{
			for(j=0; j<n; j++)
			{	
				B[i][j]=A[i][j];
			}
		}



/*-----------Calculate inverse----------*/

   for(k=0;k<n;k++)
    {
        for(i=0;i<n;i++)
        {
            if(i!=k)
		{
                if(B[n-1][n-1]== 0)
			{ 
				printf("This result requires a non-singular matrix"); 
				exit(0);
			}

                else if (B[k][k]==0)
			k++;


		M=(B[i][k]/B[k][k]);
		
                for(j=0;j<2*n;j++)
                	{

                	    B[i][j]=(B[i][j] - B[k][j]*M);
               		}

          	  }
	  }
     }

	
	for(i=0;i<n;i++)
	{
		for(j=0;j<2*n;j++)
			{
				B[i][j]=(B[i][j]/B[i][i]);
			}
	 
	}

		


        /*-------------Display matrix--------------------*/
        
	for(i=0;i<n;i++)
        {
            printf("\n");
    
            for(j=n;j<2*n;j++)
		{
            
              	  printf("%.4lf\t",B[i][j]);
            	}
        
        }

	return 0;

    }

I also tried looking for algorithms explaining the calculation, but they did not work either. I have been very frustrated over the past few days. Any help would be greatly appreciated. Thanks in advance.