redblue

REDBLUE    Shades of red and blue color map
   REDBLUE(M), is an M-by-3 matrix that defines a colormap.
   The colors begin with bright blue, range through shades of
   blue to white, and then through shades of red to bright red.
   REDBLUE, by itself, is the same length as the current figure's
   colormap. If no figure exists, MATLAB creates one.

   For example, to reset the colormap of the current figure:

             colormap(redblue)

   See also HSV, GRAY, HOT, BONE, COPPER, PINK, FLAG,
   COLORMAP, RGBPLOT.

0001 function c = redblue(m)
0002 %REDBLUE    Shades of red and blue color map
0003 %   REDBLUE(M), is an M-by-3 matrix that defines a colormap.
0004 %   The colors begin with bright blue, range through shades of
0005 %   blue to white, and then through shades of red to bright red.
0006 %   REDBLUE, by itself, is the same length as the current figure's
0007 %   colormap. If no figure exists, MATLAB creates one.
0008 %
0009 %   For example, to reset the colormap of the current figure:
0010 %
0011 %             colormap(redblue)
0012 %
0013 %   See also HSV, GRAY, HOT, BONE, COPPER, PINK, FLAG,
0014 %   COLORMAP, RGBPLOT.
0015 
0016 %   Adam Auton, 9th October 2009
0017 
0018 if nargin < 1, m = size(get(gcf,'colormap'),1); end
0019 
0020 if (mod(m,2) == 0)
0021     % From [0 0 1] to [1 1 1], then [1 1 1] to [1 0 0];
0022     m1 = m*0.5;
0023     r = (0:m1-1)'/max(m1-1,1);
0024     g = r;
0025     r = [r; ones(m1,1)];
0026     g = [g; flipud(g)];
0027     b = flipud(r);
0028 else
0029     % From [0 0 1] to [1 1 1] to [1 0 0];
0030     m1 = floor(m*0.5);
0031     r = (0:m1-1)'/max(m1,1);
0032     g = r;
0033     r = [r; ones(m1+1,1)];
0034     g = [g; 1; flipud(g)];
0035     b = flipud(r);
0036 end
0037 
0038 c = [r g b]; 
0039