Initial release of Maemo 5 port of gnuplot

[gnuplot] / demo / hexa.fnc

diff --git a/demo/hexa.fnc b/demo/hexa.fnc
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+#
+#   Use this function to fit sound velocity data as function of
+#   sound propagation direction, indicated by its angle against the
+#   z-axis of an hexagonal symmetry coordinate system
+#
+#   Adjustable parameters:
+#
+#   c33, c11, c13, c44         elastic moduli - materials constants
+#   phi0                       angle offset
+#
+# HBB 970522: factored out common factor 1e9 from c?? into the
+#  function, to improve the fit convergence. Fit parameters were
+#  just too grossly different before.
+
+rho         = 1000.0         # density in kg/m3
+
+phi(x)     = (x - phi0)/360.0*2.0*pi
+
+main(x)     = c11*sin(phi(x))**2 + c33*cos(phi(x))**2 + c44
+mixed(x)    = sqrt( ((c11-c44)*sin(phi(x))**2                          \
+                    +(c44-c33)*cos(phi(x))**2)**2  \
+                   +(2.0*(c13+c44)*sin(phi(x))*cos(phi(x)))**2 ) 
+
+vlong(x)    = sqrt(1.0/2.0/rho*1e9*(main(x) + mixed(x)))
+vtrans(x)   = sqrt(1.0/2.0/rho*1e9*(main(x) - mixed(x)))
+
+# When we read the file in, we set y=index, and we use
+# y in this (pseudo) 3d fit to choose an x function
+
+f(x,y) =  y==1  ?  vlong(x)  :  vtrans(x)