function [d]=det(a)
conta=1;
n=length(a);
for k=1:n-1
    [modpivot,l]=max(abs(a(k:n,k)));
    l=l+k-1;
    if(l~=k)
        conta=conta+1;
        auxl=a(l,k:n);
        a(l,k:n)=a(k,k:n);
        a(k,k:n)=auxl;
    end
for i=k+1:n
    mult=a(i,k)/a(k,k);
    a(i,k)=0.0;
    a(i,k+1:n)=a(i,k+1:n)-mult*a(k,k+1:n);
end
a
k
end
return
for i=1:n
    d=d*a(i,i)
end
if modconta =0
    d=-d
end
return