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Annotation of OpenXM_contrib/gnuplot/demo/reflect.fnc, Revision 1.1

1.1     ! maekawa     1: #
        !             2: #   Model function for Reflectivity evaluation
        !             3: #
        !             4:
        !             5: mu = 1.130469005513490E-001                     # (cm-1) @ 17.479 keV
        !             6: t0 = 0.18                                       # cm
        !             7: tb = 11.417823202820120 * 0.01745329251994      # thetaB (radians)
        !             8: A = mu * t0 / cos(tb)
        !             9: P = (1 + (cos(2.*tb))**2) / 2
        !            10: Fhkl = sqrt(3.536346308456155**2 + (4.58815426260982e-4)**2) * 0.968
        !            11: r0 = 2.81794092e-13                             # classical electron radius
        !            12: lambda = 7.09338062818239e-9                    # Mo K in cm
        !            13: V = 1.62253546981499e-23
        !            14: P = (1. + (cos(2.*tb))**2) / 2.
        !            15: #
        !            16: # combine constants to avoid exponential overflow on systems with
        !            17: # D floating point format where exponential limits are ca. 10**(+/-38)
        !            18: # r0liV = r0 * lambda / V
        !            19: r0liV = 2.81794092*7.09338062818239/1.62253546981499e-1
        !            20: #
        !            21:
        !            22: W(x) = 1./(sqrt(2.*pi)*eta) * exp( -1. * x**2 / (2.*eta**2) )
        !            23: Y(tc) = tc/sin(tb) * Fhkl * r0liV
        !            24: f(tc)= (tanh(Y(tc)) + abs(cos(2.*tb)) * tanh(abs(Y(tc)*cos(2.*tb)))) / (Y(tc)*(1.+(cos(2.*tb))**2))
        !            25: Q(tc) = (r0*Fhkl/V)**2 * (lambda**3/sin(2.*tb)) * P * f(tc)
        !            26: a(x) = W(x) * Q(tc) / mu
        !            27:
        !            28: #
        !            29:
        !            30: R(x) = sinh(A*a(x)) * exp(-1.*A*(1.+a(x)))