Nonlinear color scales

Q&A
1

I have a dataset which spans [-40,40] (in some units), and there are important features in the 40 magnitude range and also in the < 1 magnitude range. I would like to use a nonlinear color scale, based on tanh() to visualize all the features (small and large).

From what I understand, makecpt only supports linear color scales. Is there an easy way to build a color scale using something like tanh(z) so I can visualize both small and large features in my data?

2

Different log-scale are also supported. From what I remember, it has to go in -J parameter

3

We do linear and log10 but clearly tang etc needs to be built with coordinates via gmt math (TANH) and splice into the cpt in stead of the values there.