functions in hydra.i -

             name_array = h_array(f, ublk, name)  
          or pname_arrays = h_array(f, ublk, [name1,name2,...,nameN])  
               eq_nocopy, name_array1, *pname_arrays(1)  
               ...  
               eq_nocopy, name_arrayN, *pname_arrays(N)  
 
     reads variable array NAME for user block UBLK from the hydra file F.    
     If NAME=="matlist", you get the "Materials_matlist" array.  
     Coordinates can be obtained using the names x, y or z.  
     Ublk numbering starts at 0.  You can omit the UBLK argument and it  
     will default to zero, which is useful for problems with only a single  
     user block.  
     Note that here zone centered arrays are given using the hydra convention  
     so that i=imax, j=jmax, k=kmax are missing.  Thus in order to use the   
     Yorick plc and plf functions correctly you should index the plotted  
     variable i.e. for a 2D array.  
     plf, den(1:-1,1:-1), y, x  

             gnblk = h_blocks(f, mdims, mlens)  
 
     returns number of blocks GNBLK, block dimensions MDIMS, and  
     block lengths MLENS for the hydra mesh in file F.  
     MDIMS is 3-by-NBLK, MLENS is GNBLK elements.  

             h_close, f  
 
     close a file F opened with h_openb.  

             vart = h_collect(f, ublk, name)  
 
     returns an array of the variable NAME (a string) from user block  
     UBLK of hydra file family F.  The return value has the leading  
     dimensions of h_array(f,ublk,name), with a trailing dimension  
     representing all the times in the family.  

             name_array = h_data(f, name)  
          or pname_arrays = h_data(f, [name1,name2,...,nameN])  
               eq_nocopy, name_array1, *pname_arrays(1)  
               ...  
               eq_nocopy, name_arrayN, *pname_arrays(N)  
 
     reads variable NAME from the hydra file F.  If F is a multiblock  
     file, NAME_ARRAY will be 1-D; for single block problems it will  
     be 3-D.  If NAME=="matlist", you get the "Materials_matlist"  
     array.  Coordinates can be obtained using the names x, y or z.  
     In the second form, NAME1, ..., NAMEN are retrieved simultaneously,  
     which is useful when F is a large family of files.  
     Note that zone centered 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.  

             value = h_fparm(f, name)  
          or names = h_fparm(f)  
 
     returns value of hydra parameter NAME from file F,  
     or a list of all names in F if NAME is not supplied.  
     If NAME is not a string, returns that parameter  
     or parameters (NAME is index in the returned list of names),  
     for example h_fparm(f,1:0) returns all parameters.  

             gblk = h_gblk(f)  
 
     return global block information from the hydra file F (see h_openb).  
     Each hblk in the mesh corresponds to a particular imin:imax,  
     jmin:jmax, kmin:kmax in a particular gblk.  The return value is  
     a 2D long array 7-by-numberof(h blocks):  
     gblk(1,) =   user block number for this hblk  
     gblk(2:3,) = gblk [imin,imax] of this hblk  
     gblk(4:5,) = gblk [jmin,jmax] of this hblk  
     gblk(6:7,) = gblk [kmin,kmax] of this hblk  

             times = h_get_times(f)  
 
     return array of times in hydra history file family F.  

             value = h_global(f, name)  
 
     returns value of hydra Global variable NAME from file F.  

             value = h_iparm(f, name)  
          or names = h_iparm(f)  
 
     returns value of hydra parameter NAME from file F,  
     or a list of all names in F if NAME is not supplied.  
     If NAME is not a string, returns that parameter  
     or parameters (NAME is index in the returned list of names),  
     for example h_iparm(f,1:0) returns all parameters.  

             h_jr, f, irec  
          or nrecs = h_jr(f)  
 
     jump to record IREC in hydra history file family F.  
     In second form, return total number of records in family.  

             h_jt, f, time  
 
     jump to time TIME in hydra history file family F.  

             mixdat = h_mix(f, matlist)  
               eq_nocopy, mixn, *mixdat(1)  
               eq_nocopy, mixcell, *mixdat(2)  
               eq_nocopy, mixnmat, *mixdat(3)  
               eq_nocopy, mixhist, *mixdat(4)  
          or mix_array = h_mix(f, mixdat, name)  
          or pmix_array = h_mix(f, matlist, [name1,...,nameN], mixdat)  
               eq_nocopy, mix_array1, *pmix_array(1)  
               ...  
               eq_nocopy, mix_arrayN, *pmix_array(N)  
 
     In first form, returns MIXDAT and MATLIST for the hydra file F.  
     MIXDAT consists of two arrays: MIXN is a list of the number of  
     mixed cells for each block, and MIXCELL is an index array  
     into any hex global cell array (as returned by h_data),  
     MIXNMAT is the number of mix "zones" within each cell,  
     and MIXHIST is the list required in order to use the  
     histogram function on a mix array.  
     In the second form, reads the mix data for the variable NAME  
     in the hydra file F; the MIXDAT argument must have been returned  
     by a previous call to h_mix using the first form.  
     In the third form, MATLIST and MIXDAT are both returned along  
     with the set of variables NAME1, ..., NAMEN, so that a number of  
     variables can be retrieved in one call (useful when F is a large  
     family of files).  
     For example, to compute the temperature in each cell, using  
     a mass weighted average in mixed zones, you would do this:  
       den = h_data(f,"den");  
       tmat = h_data(f,"tmat");  
       mixdat = h_mix(f, matlist);  
       local mixcell, mixhist;  
       eq_nocopy, mixcell, *mixdat(2);  
       eq_nocopy, mixhist, *mixdat(4);  
       denx = h_mix(f, mixdat, "den");  
       tmatx = h_mix(f, mixdat, "tmat");  
       vf = h_mix(f, mixdat, "vf");  
       tavg = tmat;  
       tavg(mixcell) = histogram(mixhist, tmatx*denx*vf)/den(mixcell);  

             f = h_openb(filename)  
 
     open a hydra dump file, including 2D families of distributed  
     history files.  
     The return value is a list (see _lst function) containing the  
     currently opened file and the non-PDB data required to navigate  
     through each file and the entire family.  
     With one=1 keyword, only one file of a history family is opened.  

             value = h_parm(f, name)  
          or names = h_parm(f)  
 
     returns value of hydra parameter NAME from file F,  
     or a list of all names in NAME is not supplied.  

             h_show, f  
          or varnames = h_show(f)  
 
     prints names of variables available for h_data, h_mix, h_array.  

             ublk = h_ublk(f)  
          or ublk = h_ublk(f, unew)  
 
     return user block information from the hydra file F (see h_openb).  
     Each ublk in the mesh has a particular size.  The return value is  
     a 2D long array 7-by-numberof(u blocks):  
     ublk(1,) =   user block number for this ublk  
     ublk(2:3,) = ublk [imin,imax] of this ublk  
     ublk(4:5,) = ublk [jmin,jmax] of this ublk  
     ublk(6:7,) = ublk [kmin,kmax] of this ublk  
     Normally, imin=jmin=kmin=1, and the only information in the return  
     value is imax, jmax, kmax.  
     In the second form, sets the ublk to UNEW, which is useful for  
     resetting imin, jmin, and kmin for each block so that it describes  
     a packing of the user blocks into an overall global block  
     structure.  

 HX_blkbnd  
 
struct HX_blkbnd {  /* must match hex.h */  
  long block;  
  long cell;  
  int orient;  
}  

 HX_block  
 
struct HX_block {   /* must match hex.h */  
  long stride(3);  
  long length(3);  
  long first;  
  long final;  
}  

             hydra.i  
 
   defines several functions useful for examining and extracting  
   data from hydra-generated Silo/PDB dump files:  
   h_openb     -- use instead of openb for hydra files  
   hydra_xyz   -- extracts xyz and boundary arrays  
   h_data      -- extracts data nodal or zonal arrays  
   h_array     -- extracts data nodal or zonal arrays for one ublk  
   h_mix       -- extracts zonal data for mixed zones  
   h_iparm     -- extracts integer parameter values  
   h_gblk      -- extracts information relating hblks to  
                  user blocks  
   h_collect   -- loops on h_array over all times  

             hydra_aux_names = [name1, name2, ...];  
             mesh = hydra_mesh(f, ...);  
             eq_nocopy, var1, *hydra_aux_data(1);  
             eq_nocopy, var2, *hydra_aux_data(2);  
             ...  
 
     Set hydra_aux_names to a list of names (see h_data) in order to  
     have hydra_mesh retrieve those variables concurrently as it reads  
     the mesh.  When the mesh is spread over many files, this avoids  
     reopening and reclosing all the files, as happens if you call  
     hydra_mesh and h_data separately.  

 hydra_aux_names  
 

             hydra_mix_names = [name1, name2, ...];  
             mesh = hydra_mesh(f, ...);  
             eq_nocopy, var1, *hydra_mix_data(1);  
             eq_nocopy, var2, *hydra_mix_data(2);  
             ...  
             eq_nocopy, mixn, *hydra_mix_data(nn+1);  
             eq_nocopy, mixcell, *hydra_mix_data(nn+2);  
             eq_nocopy, mixnmat, *hydra_mix_data(nn+3);  
             eq_nocopy, mixhist, *hydra_mix_data(nn+4);  
             eq_nocopy, matlist, *hydra_mix_data(nn+5);  
 
     Set hydra_mix_names to a list of names (see h_mix) in order to  
     have hydra_mesh retrieve those variables concurrently as it reads  
     the mesh.  When the mesh is spread over many files, this avoids  
     reopening and reclosing all the files, as happens if you call  
     hydra_mesh and h_mix separately.  
     In the example, nn=numberof(hydra_mix_names).  See h_mix for a  
     description of mixn, mixcell, mixnmat, mixhist, and matlist.  

 hydra_mix_names  
 

             mesh = hydra_xyz(f)  
          or mesh = hydra_xyz(f, ublk, i0, j0, k0, face)  
          or mesh = hydra_xyz(f, ublk, i0, j0, k0)  
 
     read a 3D mesh object from the hydra PDB/Silo file F.  
     The returned mesh is _lst(xyz, bound, mbnds, blks, start).  
     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.  
     You can set a hydra_bnd_hook function before calling hydra_xyz  
     if the boundary conditions for hex need to be different than  
     for hydra.