Question

How can I plot a map area filled with colors and colors representing the values which are negative and positive. Colormap can only give colors to values in the range [0,1]. I want to increase the range.

Answer 1

Let x be the matrix with the values you want to visualize. Then you can use imagesc for a visualization:

x = (rand(100,100)-0.5)*10; % random values between -5 and 5

imagesc(x);
colorbar

Note that the colorbar is automatically adjusted to the range of date in x.