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