Change a specific color(assigned to a value) con a colorbar?

Hi, I have a colorbar that assigns the color blue to the value 0. I'd like to specifically assign the color 'white' to the value 0. How can this be done? Thank you!

Answer 1

[Walter Roberson]

cmap = colormap;       %current map
cmap(1,:) = [1 1 1];   %make first color white
colormap(cmap);        %put it into effect

[Diego Ponce de Leon Barido]

Thank you so much for your help! That was really useful.