//recursive call - see below
void determinant(complex d,complex *m,int *s,int n,int N)
{
switch(n)
{
case 1:
complex_copy(d,m[s[0]]);
break;
case 2:
unsafe_complex_prod( d,m[s[0]],m[N+s[1]]);
complex_subt_the_prod(d,m[s[1]],m[N+s[0]]);
break;
default:
complex_put_to_zero(d);
for(int p=0;p<n;p++)
{
//prepare submatrix
int l[n-1];
for(int i=0;i<p;i++) l[i]=s[i];
for(int i=p;i<n-1;i++) l[i]=s[i+1];
//compute determinant
complex in_det;
determinant(in_det,m+N,l,n-1,N);
//summ or subtract the product
void (*fun[2])(complex,complex,complex)={complex_summ_the_prod,complex_subt_the_prod};
fun[p%2](d,m[s[p]],in_det);
}
}
}
static link newlink(complex_t n, link next)
{
link l = alloc(sizeof * l);
l->entry = complex_copy(n);
l->next = next;
return l;
}
complex_t stack_pop(T t)
{
complex_t reval = complex_copy(t->head->entry);
link tmp = t->head;
t->head = t->head->next;
dellink(&tmp);
return reval;
}