---
name: "PDL::CCS::Ops"
section: "3pm"
platform: "linux"
package: "libpdl-ccs-perl"
version: "1.24.1-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/PDL::CCS::Ops"
---

# PDL::CCS::Ops(3pm)

Low-level binary operations for compressed storage sparse PDLs

## NAME

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

## SYNOPSIS

```
 use PDL;
 use PDL::CCS::Utils;
 ##---------------------------------------------------------------------
 ## ... stuff happens
```

## FUNCTIONS

### 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", *all pairs* 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.

## ACKNOWLEDGEMENTS

Perl by Larry Wall.

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

## KNOWN BUGS

No support for (pseudo)-threading.

## AUTHOR

Bryan Jurish \<moocow@cpan.org\>

### Copyright Policy

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.

## SEE ALSO

[**perl**(1)](/perl/1.md), **PDL**(3perl)