The function defines a customized colobar given the positions and the colors that are going to generate the gradients. A Live Script example is also provided to understand the following parameters:

- positions: Vector of positions, from 0 to 1. Note that the first position must be 0, and the last one must be 1.

- colors: Colors to place in each position. This parameter can be specified as a RGB matrix (n_colors x 3), or as a cell vector, containing HTML values. For instance: {'#ffffff','#ff0000','#000000'} is equivalent to [1 1 1; 1 0 0; 0 0 0].

*Update*: The function customcolormap_preset provides 8 new cool presets in order to save time configuring your own!. The presets are 'pasteljet', 'red-yellow-blue', 'red-yellow-green', 'red-white-blue', 'orange-white-purple', 'purple-white-green', 'pink-white-green', 'brown-white-pool'.

Example of use:
J = customcolormap([0 0.5 1], {'#ffffff','#ff0000','#000000'});
colorbar; colormap(J); axis off;