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

1.1     ! maekawa     1: #
        !             2: #   Use this function to fit sound velocity data as function of
        !             3: #   sound propagation direction, indicated by its angle against the
        !             4: #   z-axis of an hexagonal symmetry coordinate system
        !             5: #
        !             6: #   Adjustable parameters:
        !             7: #
        !             8: #   c33, c11, c13, c44         elastic moduli - materials constants
        !             9: #   phi0                       angle offset
        !            10: #
        !            11: # HBB 970522: factored out common factor 1e9 from c?? into the
        !            12: #  function, to improve the fit convergence. Fit parameters were
        !            13: #  just too grossly different before.
        !            14:
        !            15: rho         = 1000.0         # density in kg/m3
        !            16:
        !            17: phi(x)     = (x - phi0)/360.0*2.0*pi
        !            18:
        !            19: main(x)     = c11*sin(phi(x))**2 + c33*cos(phi(x))**2 + c44
        !            20: mixed(x)    = sqrt( ((c11-c44)*sin(phi(x))**2                          \
        !            21:                     +(c44-c33)*cos(phi(x))**2)**2  \
        !            22:                    +(2.0*(c13+c44)*sin(phi(x))*cos(phi(x)))**2 )
        !            23:
        !            24: vlong(x)    = sqrt(1.0/2.0/rho*1e9*(main(x) + mixed(x)))
        !            25: vtrans(x)   = sqrt(1.0/2.0/rho*1e9*(main(x) - mixed(x)))
        !            26:
        !            27: # When we read the file in, we set y=index, and we use
        !            28: # y in this (pseudo) 3d fit to choose an x function
        !            29:
        !            30: f(x,y) =  y==1  ?  vlong(x)  :  vtrans(x)