RGB = RGB('COLORNAME') returns the red-green-blue triple corresponding to the color named COLORNAME by the CSS3 proposed standard , which contains 139 different colors (an rgb triple is a 1x3 vector of numbers between 0 and 1). The color names are the ones accepted by almost all web browsers, for example Brown, DarkRed, SlateGray.
RGB CHART creates a figure window showing all the available colors with their names.
COLORNAME = RGB(r,g,b) and COLORNAME = RGB([r,g,b]) both find the name of the color with the triple that is closest to [r,b,g] (measured by sum of squares).
c = rgb('DarkRed') gives c = [0.5430 0 0]
c = rgb('Green') gives c = [0 0.5 0]
plot(x,y,'color',rgb('orange')) plots an orange line through x and y
rgb chart shows all the colors
cnam = rgb(0.8,0.3,0.3) gives cnam = 'IndianRed'
 "CSS Color module level 3", W3C (World Wide Web Consortium) working draft 21 July 2008, http://www.w3.org/TR/css3-color.
 "Web colors", http://en.wikipedia.org/wiki/Web_colors