79 lines
2.1 KiB
Fortran
Executable File
79 lines
2.1 KiB
Fortran
Executable File
subroutine fadpt(x,y,z,mat,nvec,time,f)
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C #####################################################################
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C
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C PURPOSE -
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C
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C Adaption function for smoothing algorithms. This is the
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C 'gyroscope' function wherein the function has large
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C second derivatives near each of three rings in the
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C three coordinate planes.
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C
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C INPUT ARGUMENTS -
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C
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C X,Y,Z - Input spatial coordinate arrays.
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C MAT - Material type arrays. (This is for cases where the
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C function value depends BOTH on position and material
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C type.)
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C NV - Length of spatial arrays. (Evaluate function at each
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C spatial coordinate.)
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C TIME - Current time (for time dependent adaption).
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C
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C OUTPUT ARGUMENTS -
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C
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C F - Array of adaption function values.
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C
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C CHANGE HISTORY -
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C
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C ######################################################################
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implicit none
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integer lenptr
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parameter (lenptr=1000000)
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real*8 x(lenptr),y(lenptr),z(lenptr),f(lenptr)
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integer nvec, i, mat(lenptr)
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real*8 r0,z0,epssq,r,dsq,x0,y0,time
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c.... Radius of rings
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r0=0.5
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c.... Center of rings
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x0=0.
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y0=0.
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z0=0.
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c.... Square of epsilon. The function does not go to infinity
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c.... on the ring because epsilon is nonzero. More precisely, the
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c.... function is
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c.... f(x,y,z)=1/( d(x,y,z)**2 +epsilon**2 ).
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c....
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c.... That is, the function is 1 divided by the smallest distance
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c.... to any of the three rings (squared) plus epsilon squared.
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c.... This implies that the 'characteristic length' of the function
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c.... AT each of the rings is epsilon.
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epssq=.1**2
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c.... Loop over vector of input values and compute function values.
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do i=1,nvec
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r=sqrt(x(i)**2+y(i)**2)
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dsq=(r-r0)**2+(z(i)-z0)**2
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r=sqrt(y(i)**2+z(i)**2)
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dsq=min(dsq,(r-r0)**2+(x(i)-x0)**2)
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r=sqrt(z(i)**2+x(i)**2)
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dsq=min(dsq,(r-r0)**2+(y(i)-y0)**2)
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f(i)=1./(dsq+epssq)
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enddo
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return
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end
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