That (interpolating colorspace) is not an option to the colormap() function.
1215 - Using Multiple Colormaps in a Single Figure
Background
Useful Properties
Example 1: Using Two Colormaps in a Single Axes
Example 2: Use a Different Colormap in Two Separate Axes
Example 3: Use Three Colormaps in a Single Axes
Example 4: Use Multiple Colormaps in a Single Figure