Colorbar with three colors

I am using surf plot the pictures. I want to see the colorbar at the right-hand side. But the transition of the color is not so obvious. I want to see from green to red, and there is another color in the middle. How can I do this?

Thanks!

[Walter Roberson]

Are there only 3 colors in the plot, or is it that you only want three colors to appear in the colorbar ?

If you are already doing colormap() in order to activate a colormap of three colors, then colorbar() should adjust automatically.

Answer 1

[KSSV]

Z = peaks(100) ;
surf(Z)
shading interp 
cmap = [1 0 0 ; 0 1 0 ; 0 0 1] ;
colorbar
colormap(cmap)