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

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)))