heapsort in Matlab

Question

Hey guys. Im trying to write an algorithm for heapsort in Matlab. Its not working. The heap is constructing fine. Filling the sorted vector is not working. Here is the code and thank you!

function [xs,h]= heap(x)
N = length(x);
h = zeros(1,N);
N_h = 0;
for i=1:N
    N_h = N_h +1;
    child = N_h;
    h(child) = x(i);
    while child>1
        parent = floor(child/2);
        if h(child)>h(parent)
            tmp = h(parent);
            h(parent) = h(child);
            h(child) = tmp;
            child = parent;
        else
            break
        end
    end

end
xs = zeros(1,N);
  parent = 1;

for i = N:-1:1
    xs(i) = h(1);
    h(1) = h(i);

    child1 = 2*parent;
    child2= 2*parent+1;

    if child1 <= i-1 


        if h(child1)>h(child2)
            cchild = child1;
        else
            cchild = child2;
        end

        if h(parent) < h(cchild)
            tmp = h(parent);
            h(parent) = h(child);
            h(child) = tmp;
            parent = child;
        else
            break
        end

    end

end