I think your advisor is just referring to the fact that if you give plot a YData array which is an MxN array, then it will plot them as M curves and give each one its own color.
Consider this example:
d = gallery('moler',16,.5); % an interesting 16x16 matrix
Executing this:
plot(1:16,d);
creates the same thing as:
hold on
for i=1:16
plot(1:16,d(i,:));
end
and it also gives each of the curves a different color.
BTW, you can also get the second example to generate different colors by using "hold all" instead of "hold on".
Also, the plot command pulls its colors from the ColorOrder property of the axes rather than the colormap. The colormap is only used by objects which have CData, such as surface or image.
