octave and matlab producing different results for following code

[bharat pathak]

k          = linspace(0, 2*pi, 100);

 

[kk, kk] = meshgrid(k, k);

 

y          = sin(kk) .* cos(kk);

 

surf( y );

 

%----------------------------------------------- running octave 3.0.1 on vista

%------------------------------------------------ running matlab 7.1 on vista