Jet/RGB Colormap with negative indices

Hi! I would like to be able to use the colorbar for negative indices, my code is the following:

number_of_colors=100;
%Intensities    %matrix with 80 values between -0.1 and 0.1 
%Maximum        %maximum value for the colormap
%Minimum        %minimum value for the colormap

%code
cmap = jet(number_of_colors);  
values = transpose(handles.Intensities(:,2)); % the intensities

% Calculate the respective index in the colormap for every value
idx_in_colorbar = floor(1+ (values - Minimum) / (Maximum -Minimum) * (number_of_colors-1));

colormatrixfunctionoutput = cmap(idx_in_colorbar,:);

The problem is that the user of the GUI defines himself the maximum and minimum value and when they are too low, idx_in_colorbar has negative values and it cannot be passed to the next line as the indices have to be positive (ERROR: Subscript indices must either be real positive integers or logicals.) Thank you for your help!

[Ignacio Lobato]

I could solve it with the following:

% Convert value of index to RGB matrix
RGB=ind2rgb(idx_in_colorbar, colm);