#include <iostream.h>
#include <math.h>
#include "array2d.h"

float Determinant(float **a,int n)
{
	int i,j,j1,j2;
	float det = 0;
	float **m = 0;
	if (n == 1) 
	{
		det = a[0][0];
	} 
   else if (n == 2) 
   {
      det = a[0][0] * a[1][1] - a[1][0] * a[0][1];
   } 
   else 
   {
		det = 0;
		for (j1=0;j1<n;j1++) 
		{
			m = allocatememory(n,n);
			for (i=1;i<n;i++) 
			{
				j2 = 0;
				for (j=0;j<n;j++) 
				{
					if (j == j1)continue;
					m[i-1][j2] = a[i][j];
					j2++;
				}
			}
			det += pow(-1.0,1.0+j1+1.0) * a[0][j1] * Determinant(m,n-1);
			freememory(m,n);
		}
	}
	return(det);
}