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Annotation of OpenXM_contrib/gnuplot/demo/density.fnc, Revision 1.1.1.1

1.1       maekawa     1: #
                      2: #   This is a rough approach to fit a model function to the density
                      3: #   data of a liquid crystal. The function consists of a linear
                      4: #   branch for the high temperature region and of a curved branch with
                      5: #   linear asymptote for the low temperatuer branch
                      6: #
                      7:
                      8: #   free parameters:
                      9: #   m1, m2  slopes of the linear function in the low and high T region
                     10: #   Tc     transition temperature
                     11: #   dens_Tc density at the transition temperature
                     12: #   g      factor to scale tanh function
                     13:
                     14: ml     = -0.0001
                     15: mh     = -0.0001
                     16: dens_Tc = 1.020
                     17: Tc     = 45
                     18: g      = 1
                     19: b      = 0.1
                     20:
                     21:
                     22: high(x) = mh*(x-Tc) + dens_Tc
                     23: lowlin(x)  = ml*(x-Tc) + dens_Tc
                     24: curve(x) = b*tanh(g*(Tc-x))
                     25:
                     26: density(x) = x < Tc ? curve(x)+lowlin(x) : high(x)