function [a,b]=gauss1(a,b)
n=length(b);
for k=1:n-1
    [modpivot,l]=max(abs(a(k:n,k)));
    l=l+k-1;
    if(l~=k)
        auxl=a(l,k:n);
        a(l,k:n)=a(k,k:n);
        a(k,k:n)=auxl;
        auxb=b(l);
        b(l)=b(k);
        b(k)=auxb;
    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);
    b(i)=b(i)-mult*b(k);
end
a,b
k
end
return