deltaR2 = r20a - r20b
alpha_m = deltaR2 + k_AB - k_BA
zeta = 2 * dw * alpha_m
Psi = alpha_m**2 + 4 * k_BA * k_AB - dw**2
And put the g_fact = 1/sqrt(2), inside the library function.
It made no sense to put these calculations outside the library, since there would be no skipping of a loop.
It actually makes much better sense to keep these calculation in the library function, to preserve the possibility
to import this module in other software.
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
