How does surf map colormatrix

I know surf(x,y,z,c) will use matrix c to map color, but how does it work? since matrix c actually has the size of z, instead of size of z x 3 (that's what I thought first, for I thought you specified the RGB for each element of z), how does matlab map c to different color schemes? For example,

surf(x,y,z,c); colormap winter

So how does matlab find the corresponding color based on c?

Answer 1

[Walter Roberson]

It uses the standard color mapping techniques: min value of c maps to the lowest entry in the color map, max value of c maps to the highest entry in the color map, everything in between maps linearly in to color map index numbers.

You can change properties to change the mapping strategy.

[Qianyu]

Thank you. Now it makes sense to me. So if I don't use c, then the values of z will be mapped the same way, right?

[Walter Roberson]

If you do not use c then z will be copied to the internal property that c would otherwise go in (CData) and then the mapping proceeds in exactly the same way.