Can any 1 help me in implementing a fast determinant evaluator

i have a wriiten a code but its way too slow when determinant size is 1000x1000

any links..suggestions would do

Code:

#include <iostream>
using namespace std;
int determinant(int size,int det[][100]) // size & row of the square matrix
{
int temp[100][100],a=0,b=0,i,j,k;
int sum=0,sign; /* sum will hold value of determinant of the current matrix */
if(size==2) return (det[0][0]*det[1][1]-det[1][0]*det[0][1]);
sign=1;
for(i=0;i<size;i++) // note that 'i' will indicate column no.
{
a=0;
b=0;
// copy into submatrix and recurse
for(j=1;j<size;j++) // should start from the next row !!
{
for(k=0;k<size;k++)
{
if(k==i) continue;
temp[a][b++]=det[j][k];
}
a++;
b=0;
}
sum+=sign*det[0][i]*determinant(size-1,temp); // increnting row & decrementing size
sign*=-1;
}
return sum;
}
int main()
{
int i,j,det[100][100];
for(i=0;i<6;i++)
for(j=0;j<6;j++)
cin>>det[i][j];
cout<<endl;
cout<<determinant(6,det)<<endl;
}

Thank u !