Speed-up. Moved g_factor: g = 1/sqrt(2) outside library function to be calculated once.
sr #3154: (https://gna.org/support/?3154) Implementation of Baldwin (2014) B14 model - 2-site exact solution model for all time scales.
This follows the tutorial for adding relaxation dispersion models at:
http://wiki.nmr-relax.com/Tutorial_for_adding_relaxation_dispersion_models_to_relax#Debugging
