cmapsign

 function f = cmapsign(n)

 <n> (optional) is desired number of entries
   default: 64

 return a blue-black-red colormap.
 suitable for ranges like [-X X].

 example:
 figure; imagesc(randn(100,100)); axis equal tight; colormap(cmapsign); colorbar;

0001 function f = cmapsign(n)
0002 
0003 % function f = cmapsign(n)
0004 %
0005 % <n> (optional) is desired number of entries
0006 %   default: 64
0007 %
0008 % return a blue-black-red colormap.
0009 % suitable for ranges like [-X X].
0010 %
0011 % example:
0012 % figure; imagesc(randn(100,100)); axis equal tight; colormap(cmapsign); colorbar;
0013 
0014 % inputs
0015 if ~exist('n','var') || isempty(n)
0016   n = 64;
0017 end
0018 
0019 % constants
0020 colors = [
0021   0 0 1  % blue
0022   0 0 0  % black
0023   1 0 0  % red
0024   ];
0025 
0026 % do it (MAYBE CONSOLIDATE THIS CODE?)
0027 f = [];
0028 for p=1:size(colors,2)
0029   f(:,p) = interp1(linspace(0,1,size(colors,1)),colors(:,p)',linspace(0,1,n),'linear');
0030 end
0031 
0032 
0033 % OLD
0034 % f = colorinterpolate(colors,31,1);