how to insert RGB percentage colors in a vector?

Hello, I wrote a code that produces polynomiographic drawings of input polynomials I put all the colors in a vector that are coded with a letter but i want more colors so i can input polynomials of higher grades but nothing seems to work. here is the code i have

function [ y ] = polyn( f,df,c)
nulpt=roots(c);
k=['r' 'y' 'b' 'g' 'm' 'c' 'w' 'k'];
      d=numel(nulpt);
for a=(-1.5:10^(-2):1.5)
  for    b=(-1.5:10^(-2):1.5)
      x=a+b*1i;
      y=newton(f,df,x);
      for l=1:d 
          if abs(y-nulpt(l))<10^(-2)
              plot(a,b,'.', 'Color', k(l))
              hold on

            end 
            end
        end
    end
end
this works fine but i want more colors in k i have tried naming a color like r=[1 1 1] or just put the vector in k but nothing seems to work

Answer 1

[Image Analyst]

You have to make k an N by 3 colormap (array). So if you want certain specific non-standard colors, you can't use letters anymore -- you need 3 numbers.

k = [...
1,0,0
1,1,0
0,0,1
0,1,0
1,0,1
etc....

plot(a,b,'.', 'Color', k(l, :));

[nick Luyten]

thanks for youre time and efford. This really is a big help :D

[Image Analyst]

You're welcome. Actually you can mix arrays and letters if you use cell arrays, like Guillaume showed. Cell arrays are more complicated and confusing but sometimes necessary. Read the FAQ if you want to get a good feeling for how to use them: http://matlab.wikia.com/wiki/FAQ#What_is_a_cell_array.3F

Answer 2

[Guillaume]

As defined, your k is just:

k = 'rybgmcwk';

since a matrix of characters is just a string.

You can solve your problem, by either

1. Putting your colours in a cell array. That way you can mix colour strings and RGB values

k = {'r' 'y' 'b' 'g' 'm' 'c' 'w' 'k' [1 .2 .5] [.3 .6 .9]}; %for example
assert(numel(k) >= d); %otherwise you've got a problem
%...
   plot(a, b, '.', 'Color', k{l});

2. Putting your colours in a d*3 matrix. You can only have RGB values

k = [1   1   1
     0   1   1 
     1   0   0
     0.2 0.4 0.6]; %for example
assert(size(k, 1) >= d); %otherwise you've got a problem
%...
    plot(a, b, '.', 'Color', k(l, :));

3. Change the ColorOrder property of the axes and not bother specifying colours in your plot:

k = [1   1   1
     0   1   1 
     1   0   0
     0.2 0.4 0.6]; %for example
assert(size(k, 1) >= d); %otherwise you've got a problem
haxes = gca;
haxes.ColorOrder = k; %use set pre-R2014b
hold on
%...
    plot(a, b, '.');

[nick Luyten]

Thanks verry much. I ended up using your first solution

Answer 3

[Thorsten]

To get, e.g,, 10 different colors, you can define your colormap like

cm = jet(10);

or using http://www.mathworks.com/matlabcentral/fileexchange/29702-generate-maximally-perceptually-distinct-colors

cm = distinguishable_colors(10);

and then plot

hold on, for i = 1:10, plot(rand(1, 20), 'Color', cm(i,:)), end

Answer 4

[nick Luyten]

Thank you verry much all for your time and effort. It was a great help