Detrminent of a Matrix in C

#include <stdio.h>
#include <conio.h>
#include <math.h>
#include <windows.h>
#define MAX 3
void matrix ( int [3][3] ) ;
void create ( int [3][3] ) ;
void display ( int [3][3] ) ;
void matmul ( int [3][3], int [3][3], int [3][3] ) ;
void transpose ( int [3][3], int [3][3] ) ;
double determinant ( int [3][3] ) ;
int isortho ( int [3][3] ) ;
int main( )
{
 int mat [3][3] ;
 double d ;
 system ( "cls" ) ;
 printf ( "Enter elements for array:\n\n" ) ;
 create ( mat ) ;
 printf ( "The Matrix:\n" ) ;
 display ( mat ) ;
 d = determinant ( mat ) ;
 printf ( "The determinant for given matrix: %d.\n\n", d ) ;
 if ( d == 0 )
  printf ( "Matrix is singular.\n\n" ) ;
 else
  printf ( "Matrix  is not singular.\n\n" ) ;
 d = isortho ( mat ) ;
 if ( d != 0 )
  printf ( "Matrix is orthogonal.\n\n" ) ;
 else
  printf ( "Matrix is not orthogonal.\n\n" ) ;
 return 0 ;
}
/* initializes the matrix mat with 0 */
void matrix ( int mat[3][3] )
{
 int i, j ;
 for ( i = 0 ; i < MAX ; i++ )
 {
  for ( j = 0 ; j < MAX ; j++ )
   mat[i][j] = 0 ;
 }
}
/* creates matrix mat */
void create ( int mat[3][3] )
{
 int n, i, j ;
 for ( i = 0 ; i < MAX ; i++ )
 {
  for ( j = 0 ; j < MAX ; j++ )
  {
   printf ( "Enter the element: " ) ;
   scanf ( "%d", &n ) ;
   mat[i][j] = n ;
  }
 }
 printf ( "\n" ) ;
}
/* displays the contents of matrix */
void display ( int mat[3][3] )
{
 int i, j ;
 for ( i = 0 ; i < MAX ; i++ )
 {
  for ( j = 0 ; j < MAX ; j++ )
   printf ( "%d\t", mat[i][j] ) ;
  printf ( "\n" ) ;
 }
 printf ( "\n" ) ;
}
/* multiplies two matrices */
void matmul ( int mat1[3][3], int mat2[3][3], int mat3[3][3] )
{
 int i, j, k ;
 for ( k = 0 ; k < MAX ; k++ )
 {
  for ( i = 0 ; i < MAX ; i++ )
  {
   mat3[k][i] = 0 ;
   for ( j = 0 ; j < MAX ; j++ )
    mat3[k][i] += mat1[k][j] * mat2[j][i] ;
  }
 }
}
/* obtains transpose of matrix m1 */
void transpose ( int mat[3][3], int m[3][3] )
{
 int i, j ;
 for ( i = 0 ; i < MAX ; i++ )
 {
  for ( j = 0 ; j < MAX ; j++ )
    m[i][j] = mat[j][i] ;
 }
}
/* finds the determinant value for given matrix */
double determinant ( int mat[3][3] )
{
 int i, j, k ;
 double sum, p ;
 sum = 0.0 ; j = 1 ; k = MAX - 1 ;
 for ( i = 0 ; i < MAX ; i++ )
 {
  p = pow ( -1.0, i ) ;
  if ( i == MAX - 1 )
   k = 1 ;
  sum = sum + ( mat[0][i] * ( mat[1][j] *
         mat[2][k] - mat[2][j] *
         mat[1][k] ) ) * p ;
  j = 0 ;
 }
 return sum ;
}
/* checks if given matrix is an orthogonal matrix */
int isortho ( int mat[3][3] )
{
 /* transpose the matrix */
 int m1[3][3], m2[3][3], i ;
 transpose ( mat, m1 ) ;
 /* multiply the matrix with its transpose */
 matmul ( mat, m1, m2 ) ;
 /* check for the identity matrix */
 for ( i = 0  ; i < MAX ; i++ )
 {
  if ( m2[i][i] == 1 )
   continue ;
  else
   break ;
 }
 if ( i == MAX )
  return 1 ;
 else
  return 0 ;
}