1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
|
#
# 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)
|
