c code to find the determinant of a matrix.

code to find the determinant of a matrix:

#include<stdio.h>
int n;
void swap(float * a,float * b)
{
  float t;
  t=*a;
  *a=*b;
  *b=t;
  return;
  }
 
  void print_mat(float a[100][100])
  {
   int i,j;
    for (i=0;i<n;i++)
   {
   for(j=0;j<n;j++)
   {
     printf("%f  ",a[i][j]);
    }
     printf("\n");}
     }
    
void row_change(float * a,float * b)
  {
  int i;
    for (i=0;i<n;i++)
    {
      swap (&a[i],&b[i]);
      }
      return;}

  void row_trans(float * a,float *b,float f)
  {int i;
   for (i=0;i<n;i++)
   {
     a[i]=a[i]+f*b[i];
     }
     return;
   }
  
/* int **extract(int a[s][s],int j)
 {
    int k,l,i;
    int b[s-1][s-1];
    for (k=1;k<s;k++)
    {
      for (i=0,l=0;l<s && l !=j;l++)
      {
         b[k-1][i]=a[k][l];
         i++;
      }
    }
    return b;
  }*/

main ()
{
  float a[100][100];
  scanf("%d",&n);
  int i,j,k,count=0;
  for (i=0;i<n;i++)
  {
     for (j=0;j<n;j++)
     {
        scanf("%f",&a[i][j]);
      }
   }
       print_mat(a);
   for (i=0;i<n;i++)
     {
        if (a[i][i]==0)
        {
          for (j=i;j<n;j++)
              {
                if (a[j][i] !=0)
                 {
                   row_change(a[i],a[j]);
                   count=count+1;
                   break;
                 }
               }
           if (a[i][i] == 0)
              {
                for (j=i;j<n;j++)
                {
                  if(a[i][j] !=0)
                  {
                    for (k=0;k<n;k++)
                    { if (k !=i)
                      {
                        row_trans(a[k],a[i],-a[k][j]/a[i][j]);
                      }
                    }
                     break;
                   }
                 }
              }
          }   
       else
        {
            for (j=0;j<n;j++)
              {
                 if (j !=i)
                  {
                     row_trans(a[j],a[i],-a[j][i]/a[i][i]);
                   }
               }
         } 
     }
     print_mat(a);
     float pro=1;
     for (i=0;i<n;i++)
     {
        pro=pro*a[i][i];
     }
     if (count%2==0)
     {
        printf("%f\n",pro);
      }
      else
      printf("%f\n",-1*pro);
} 
you may wonder why the extract function is written there in comments...just to facilitate you get the cofactor of an element.