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functions in hex.i -
bi_dir
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nlist = bi_dir(tracker, mesh, rays, slimits, c, s)
Perform hexX_track and track_reduce on a ray that enters
the problem at the given point on the ray. This requires
tracking the ray in both directions from the given point,
hence this function name indicating bi-directional tracking.
This is unnecessary when the entry point search was over
the problem boundary, or when the SLIMITS for the rays
always lie in one direction relative to the starting point.
TRACKER is the function used to track the rays, normally
one of hex5_track, hex_24f_track, or hex24b_track.
MESH is the problem mesh returned by hex_mesh or hydra_mesh;
it should be generated using the entry option that finds
the cell containing the given point on the ray.
RAYS is the 3-by-nrays-by-2 array of rays, as for hex5_track
SLIMITS is nil or the ray tracking limits as for track_reduce
C, S, together with NLIST are the output arrays, as for
track_reduce
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SEE ALSO:
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track_reduce,
hex5_track,
hex24f_track,
hex24b_track,
track_combine
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c_adjust
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c_adjust, c, mesh
or c_adjust, c, mesh, 1
or c= c_adjust(c, mesh, how)
adjust the cell number array C returned by track_reduce to
allow for a different layout of cell arrays than the one assumed
by the tracking routines. Two HOW values are currently
supported: 0 (or nil) if the cell arrays are the same shape as
the nodal arrays, but the non-existent cell is at the end of
each row rather than at the beginning. And 1 if the cell arrays
are smaller by one along each dimension than the nodal arrays.
If you call c_adjust as a subroutine, the input C array
is modified; if you call it as a function, the input C is
unchanged and the new values returned.
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SEE ALSO:
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track_reduce,
hex5_track,
cs_adjust
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conv3_rays
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conv3_rays(rays)
convert [p,q] representation to or from best_rays representation.
If the first dimension of RAYS is 3, returns 5-by-raydims array
of best_rays; if first dimension of RAYS is 5, returns 3-by-raydims-
by-2 [p,q] for use with hex5_track.
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SEE ALSO:
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hex5_track,
pic3_rays,
best_rays
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cs_adjust
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nlist= cs_adjust(nlist, c, s, ireg)
adjust NLIST, C, S returned from track_reduce to remove transits
of cells for which IREG == 0. Can be called before or after
c_adjust, depending on layout of IREG.
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SEE ALSO:
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c_adjust
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hex5_track
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c= hex5_track(mesh, rays, s)
c= hex24f_track(mesh, rays, s)
c= hex24b_track(mesh, rays, s)
track 3 x Nrays x 2 RAYS through the 3D MESH. RAYS(,,1) are
points on the rays, while RAYS(,,2) are normalized ray directions.
The c return value and the S parameter are a long and double
array respectively, with number of elements equal to the total
number of intersections of all the RAYS with faces of the MESH,
plus one for any RAY which misses MESH entirely. The values of
c are:
[#hits,cell1,cell2,cell3,..., #hits,cell1,cell2,cell3,..., ...]
where each #hits is followed by the list of cell indices (assuming
i=1, j=1, and k=1 are present but meaningless in cell arrays --
that is, assuming zone centered arrays have the same dimensions
as XYZ rather than one less in each direction). Rays which miss
the mesh entirely have #hits=1, all others have #hits>=2 since they
must exit. #hits<0 means a ray reentered the mesh for abs(#hits)
more face crossings, but this currently cannot happen. The values
of S correspond to c:
[s0,s1,s2,s3,..., s0,s1,s2,s3,..., ...]
which are the distances along the ray measured from RAYS(,,1) in
the direction of RAYS(,,2) where the ray pierces a cell face. For
rays which miss the mesh, the value of s0 is a diagnostic telling
why they missed (see compiled code).
Function hex5_track uses the 5-tet decomposition for hexes,
which is not unique when the quad faces are non-planar. You may
be able to get an idea of this effect by setting hex_triang the
opposite way and redoing the trace.
Functions hex24f_track and hex24b_track use the face and body
centered 24-tet decompositions for hexes. These are unique;
however, hex_triang may in rare cases change the trace slightly,
since the entry search algorithm still involves triangulating
the surface quads.
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SEE ALSO:
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hydra_mesh,
hex_triang,
reg_track,
track_reduce,
c_adjust,
pic3_rays,
conv3_rays
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hex_mesh
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mesh= hex_mesh(xyz, bound, nbnds, &mbnds, nblk, &blks, start)
create a 3D mesh object from the multiblock mesh parameters
XYZ is NBLK 3 x Ni x Nj x Nk coordinate arrays packed together
BOUND is NBLK 3 x Ni x Nj x Nk face boundary markers packed
NBNDS is length of MBNDS
MBNDS is HX_blkbnd describing each internal block boundary face
NBLK is number of blocks
BLKS is NBLK HX_block objects describing the block structure
START is 0-origin 6*cell+face index of first boundary face/cell
or -1-cell to trace from centroid of that cell to point
p on ray to begin tracking
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SEE ALSO:
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hex5_track,
hydra_mesh,
hex_startflag
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hex_mesh2
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mesh= hex_mesh2(xyz, bounds)
old interface for hex_mesh
create a 3D mesh object from the 3 x Ni x Nj x Nk coordinate
array XYZ and the list of 6 BOUNDS:
BOUNDS(1), BOUNDS(2) for the i=1,Ni boundaries
BOUNDS(3), BOUNDS(4) for the j=1,Nj boundaries
BOUNDS(5), BOUNDS(6) for the k=1,Nk boundaries
The BOUNDS values are:
1 if this is a problem boundary
2 if this is a reflecting boundary
3 if this is a periodic boundary
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SEE ALSO:
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hydra_mesh
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hex_query
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start= hex_query(mesh, xyz, bound, mbnds, blks)
query a mesh created by hex_mesh, returning the arrays
passed to that function (these are not copies -- be careful
not to clobber them)
function return value is the start index
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SEE ALSO:
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hex5_track,
hydra_mesh
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hex_startflag
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old_flag= hex_startflag(new_flag)
possibly set flag to NEW_FLAG, always return OLD_FLAG, where
flag value is 0 (default) to begin search for new entry point
at previous entry point, 1 to begin search for new entry point
from mesh start face for every ray. Any other value of NEW_FLAG
returns OLD_FLAG without changing it.
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SEE ALSO:
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hex_mesh
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hex_triang
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old_flag= hex_triang(new_flag)
possibly set flag to NEW_FLAG, always return OLD_FLAG, where
flag value is 0 for default mesh triangulation, 1 for opposite
triangulation, and 2 on input to signal not to change the
current value. The triangulation value can affect the result
of hex5_track if the quad faces of the mesh are not planar.
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SEE ALSO:
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hex5_track
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hydra_mesh
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mesh= hydra_mesh(f)
or mesh= hydra_mesh(f, ublk, i0, j0, k0, face)
or mesh= hydra_mesh(f, ublk, i0, j0, k0)
read a 3D mesh object from the hydra PDB/Silo file F.
Note that the boundary arrays are adjusted to the hex convention
that cells with i=1, j=1, k=1 are missing, rather than the hydra
convention that i=imax, j=jmax, k=kmax are missing.
In the first form, the ray entry search will start on the
first open boundary face in the mesh. If the actual problem
boundary is not convex, you need to identify a surface of
constant i, j, or k in the problem which is convex, and which
all the rays you intend to trace intersect.
UBLK is the user block number (starting from 0),
I0, J0, K0 are the (1-origin) logical coordinates of a
hydra *cell*. Note that unlike hex cells, the hydra
cell bounded by nodes (1,1,1) and (2,2,2) is numbered (1,1,1).
(Hex numbers it (2,2,2).)
FACE is the face number on cell (I0,J0,K0) which you want a
ray to enter. 0 means the -I face, 1 the +I face, 2 the -J
face, 3 the +J face, 4 the -K face, and 5 the +K face.
As you step from this cell to its neighbors, then to their
neighbors, and so on, this face must trace out a convex
surface for the ray entry search. Rays not intersecting
this surface will not enter the problem; the ray trace
will begin at this surface, not at -infinity.
If FACE==-1 or is omitted (as in the third form), then the
given points on the rays are assumed to lie inside the mesh,
and a pseudo ray from the centroid of cell (I0, J0, K0) will be
tracked to the given point on each ray; the ray will be launched
into the cell containing that point.
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SEE ALSO:
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hex_query,
hex5_track,
h_data,
h_openb
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hydra_start
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hydra_start, mesh, start
change the starting cell of the hydra MESH (returned by hydra_mesh)
to START. If called as a function, returns old start value.
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SEE ALSO:
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hydra_mesh,
h_data
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make_sphere
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make_sphere(radius, [imax,jmax,kmax],
[phi1, phi2], [theta1, theta2])
return a mesh (see hex_mesh) representing the given section
of the sphere of given RADIUS. IMAX, JMAX, and KMAX are the
number of nodes (cells+1) in the radial, longitude (phi), and
colatitude (theta) directions, respectively. Note that for
a right handed coordinate system, phi1theta2.
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SEE ALSO:
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hex_mesh
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pic3_rays
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rays= pic3_rays(xpict, ypict, ray)
or rays= pic3_rays(xpict, ypict, ray, q_up)
Like picture_rays, but returns rays in the [p,q] representation
appropriate for hex5_track.
(XPICT,YPICT) are 2D arrays of pixel corners in the image plane;
RAY is the central ray (0,0) in (XPICT,YPICT) coordinates, given
in [p,q] representation (i.e. RAY is a 3-by-2 array). The
optional Q_UP is a 3-vector specifying the orientation of the
y-axis in the picture plane (see theta_up, phi_up in picture_rays
for a description of default orientation). Q_UP must not be
parallel to RAY(,2).
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SEE ALSO:
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hex5_track,
conv3_rays,
picture_rays
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reg_track
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c= reg_track(x, y, z, rays, s)
track RAYS through regular mesh defined by the 1D coordinate
arrays X, Y, and Z. Return values S and C are as for
hex5_track, where the mesh is numberof(X) by numberof(Y) by
numberof(Z).
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SEE ALSO:
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hex5_track,
track_reduce
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track_combine
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nlist = track_combine(nm,cm,sm, np,cp,sp, c, s)
combine two track_reduce results NM,CM,SM, and NP,CP,SP,
which represent the first and second halves of a set of
rays. See bi_dir for a typical application. The returned
NLIST is NM+NP, or NM+NP-1 for those rays where the
final CM is identical to the initial CP.
C, S, together with NLIST are the output arrays, as for
track_reduce.
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SEE ALSO:
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track_reduce,
bi_dir
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track_integ
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result= track_integ(nlist, transp, selfem, last)
integrates a transport equation by doing the sums:
transparency(i) = transparency(i-1) * TRANSP(i)
emissivity(i) = emissivity(i-1) * TRANSP(i) + SELFEM(i)
returning only the final values transparency(n) and emissivity(n).
The NLIST is a list of n values, so that many transport integrals
can be performed simultaneously; sum(NLIST) = numberof(TRANSP) =
numberof(SELFEM). The result is 2-by-dimsof(NLIST).
If TRANSP is nil, result is dimsof(NLIST) sums of SELFEM.
If SELFEM is nil, result is dimsof(NLIST) products of TRANSP.
TRANSP and SELFEM may by 2D to do multigroup integrations
simultaneously. By default, the group dimension is first, but
if LAST is non-nil and non-zero, the group dimension is second.
In either case, the result will be ngroup-by-2-by-dimsof(NLIST).
track_solve is the higher-level interface.
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SEE ALSO:
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track_reduce,
track_solve,
track_solve
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track_reduce
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nlist= track_reduce(c, s)
or nlist= track_reduce(c, s, rays, slimits)
compresses the C and S returns from the tracking routines (see
hex5_track) to the following form:
[cell1,cell2,cell3,..., cell1,cell2,cell3,..., ...]
[s1-s0,s2-s1,s3-s2,..., s1-s0,s2-s1,s3-s2,..., ...]
returning nlist as
[#hits, #hits, ...]
In this form, any negative #hits are combined with the preceding
positive values, and #hits=1 (indicating a miss) appear as #hits=0
in nlist. Hence, nlist always has exactly Nrays elements.
If RAYS is supplied, it is used to force the dimensions of the
returned nlist to match the dimensions of RAYS (the value of RAYS
is never used). The RAYS argument need not have the trailing 2
dimension, so if you specified RAYS as [P,Q] if the call to
hex5_track, you can use just P or Q as the RAYS argument to
track_reduce.
If SLIMITS is supplied, it should be [smin,smax] or [smin,smax]-
by-dimsof(nlist) in order to reject input S values outside the
specified limits. The C list will be culled appropriately, and
the first and last returned ds values adjusted.
With a non-zero flip= keyword, the order of the elements of
C and S within each group of #hits is reversed, so that a
subsequent track_solve will track the ray backwards. If you
use this, both the ray direction input to the tracking routine
and any SLIMITS argument here should refer to the reverse of
the ray you intend to track.
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SEE ALSO:
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hex5_track,
c_adjust,
track_solve,
track_integ,
bi_dir,
track_combine
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track_solve
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result= track_solve(nlist, c, s, akap, ekap, last)
integrates a transport equation for NLIST, C, and S returned
by track_reduce (and optionally c_adjust). The RAYS argument
is used only to set the dimensions of the result. AKAP and
EKAP are mesh-sized arrays of opacity and emissivity, respectively.
They may have an additional group dimension, as well. The
units of AKAP are 1/length (where length is the unit of S),
while EKAP is (spectral) power per unit area (length^2), where
the power is what ever units you want the result in. The
emission per unit volume of material is EKAP*AKAP; an optically
thick block of material emits EKAP per unit surface.
The NLIST is a list of n values, so that many transport integrals
can be performed simultaneously; sum(NLIST) = numberof(AKAP) =
numberof(EKAP). The result is 2-by-dimsof(NLIST), where the
first element of the first index is the transmission fraction
through the entire ray path, and the second element of the
result is the self-emission along the ray, which has the same
units as EKAP.
If EKAP is nil, result is dimsof(NLIST) -- exactly the same as
the transparency (1st element of result) when both EKAP and AKAP
are specified.
If AKAP is nil, result is dimsof(NLIST). In this case, EKAP
must have units of emission per unit volume instead of per unit
area; the result will be the sum of EKAP*S along each ray.
AKAP and EKAP may by 2D to do multigroup integrations
simultaneously. By default, the group dimension is first, but
if LAST is non-nil and non-zero, the group dimension is last.
In either case, the result will be ngroup-by-2-by-dimsof(NLIST).
To use in conjuction with hex5_track, one might do this:
c= hex5_track(mesh, rays, s);
nlist= track_reduce(c, s, rays);
c_adjust, c, mesh; // if necessary
result= track_solve(nlist, c, s, akap, ekap);
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SEE ALSO:
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track_reduce,
hex5_track
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