I want to create a patch where a sphere can change to one of seven colours. I would like these to be evenly spaced along the colour spectrum. So the colours: Red, Orange, Yellow, Green, Blue, Indigo and Violet; or something there about.

I've read a fair bit about RGB. However I'm not sure how one would do this in math. It seems it would be easier to do it if there was a "Hue" control. However I'd like to learn it this way.

So basically I'm just looking for a point in the right direction

Thanks

maybe you want the hsv color model
i just would do a linear or quadratic interpolation between the two colors

I think [hsv2rbg] is what you are looking for. Give a look at the patch below.

http://www.pdpatchrepo.info/hurleur/hsvColor.zip

Brilliant. Thank you so much. That's just what I was after.