#

#   This is a rough approach to fit a model function to the density

#   data of a liquid crystal. The function consists of a linear

#   branch for the high temperature region and of a curved branch with

#   linear asymptote for the low temperatuer branch

#

#   free parameters:

#   m1, m2  slopes of the linear function in the low and high T region

#   Tc	    transition temperature

#   dens_Tc density at the transition temperature

#   g	    factor to scale tanh function

ml	= -0.0001

mh	= -0.0001

dens_Tc = 1.020

Tc	= 45

g	= 1

b	= 0.1

high(x) = mh*(x-Tc) + dens_Tc

lowlin(x)  = ml*(x-Tc) + dens_Tc

curve(x) = b*tanh(g*(Tc-x))

density(x) = x < Tc ? curve(x)+lowlin(x) : high(x)