PDL::CCS::Ops - Low-level binary operations for compressed storage sparse PDLs

       Perl by Larry Wall.

       PDL by Karl Glazebrook, Tuomas J. Lukka, Christian Soeller, and others.

       Bryan Jurish <moocow@cpan.org>

   CopyrightPolicy
       All other parts Copyright (C) 2007-2024, Bryan Jurish. All rights reserved.

       This package is free software, and entirely without warranty.  You may redistribute it and/or modify it
       under the same terms as Perl itself.

ccs_binop_align_block_mia
         Signature: (
           indx ixa(Ndims,NnzA); indx ixb(Ndims,NnzB); indx    istate(State);
           indx [o]nzai(NnzC);   indx [o]nzbi(NnzC);   indx [o]ostate(State);
           )

       Partially aligns a pair of lexicographically sorted index-vector lists $ixa() and $ixb(), e.g. for block-
       wise incremental computation of binary operations over sparse index-encoded PDLs, assuming missing
       indices correspond to annihilators.

       On return, the vectors $nzai and $nzbi hold indices into "NnzA" and "NnzB" respectively, and are
       constructed such that:

        ($ixa(,$nzai->slice("0:$nzci_max")) == $ixb(,$nzbi->slice("0:$nzci_max"))

       At most "NnzC" alignments are performed, and alignment ceases as soon as any of the PDLs $ixa(), $ixb(),
       $nzai(), or $nzbi() has been exhausted.

       The parameters $istate() and $ostate() hold the state of the algorithm, for incremental block-wise
       computation at the perl level.  Each state PDL is a 7-element PDL containing the following values:

        INDEX LABEL       DESCRIPTION
        -----------------------------------------------------------------------
          0   nnzai       minimum offset in NnzA of current $ixa() value
          1   nnzai_nxt   minimum offset in NnzA of next $ixa() value
          2   nnzbi       minimum offset in NnzB of current $ixb() value
          3   nnzbi_nxt   minimum offset in NnzB of next $ixb() value
          4   nnzci       minimum offset in NnzC of current ($ixa(),$ixb()) value pair
          5   nnzci_nxt   minimum offset in NnzC of next ($ixa(),$ixb()) value pair
          6   cmpval      3-way comparison value for current ($ixa(),$ixb()) value pair

       For computation of the first block, $istate() can be safely set to "zeroes(long,7)".

       Repetitions may occur in input index PDLs $ixa() and $ixb().  If an index-match occurs on such a "run",
       allpairs of matching values are added to the output PDLs.

       All alignments have been performed if:

        $ostate(0)==$NnzA && $ostate(1)==$NnzB

       WARNING: this alignment method ignores index-vectors which are not present in both $ixa() and $ixb(),
       which is a Good Thing if your are feeding the aligned values into an operation for which missing values
       are annihilators:

        $missinga * $bval     == ($missinga * $missingb)  for each $bval \in $b, and
        $aval     * $missingb == ($missinga * $missingb)  for each $aval \in $a

       This ought to be the case for all operations if missing values are "BAD" (see PDL::Bad), but might cause
       unexpected results if e.g. missing values are zero and the operation in question is addition.

       ccs_binop_align_block_mia does not process bad values.  It will set the bad-value flag of all output
       ndarrays if the flag is set for any of the input ndarrays.

       No support for (pseudo)-threading.

       PDL::CCS::Ops - Low-level binary operations for compressed storage sparse PDLs

perl(1), PDL(3perl)

perl v5.40.0                                       2025-01-04                                           Ops(3pm)

        use PDL;
        use PDL::CCS::Utils;

        ##---------------------------------------------------------------------
        ## ... stuff happens