

 
Manual Reference Pages  PDL::MATRIX (3)
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NAME
PDL::Matrix  a convenience matrix class for columnmajor access
CONTENTS
VERSION
This document refers to version PDL::Matrix 0.5 of PDL::Matrix
SYNOPSIS
use PDL::Matrix;
$m = mpdl [[1,2,3],[4,5,6]];
$m = PDL::Matrix>pdl([[1,2,3],[4,5,6]]);
$m = msequence(4,3);
@dimsa = $a>mdims; # dims is not overloaded
$v = vpdl [0,1,2,3]
$v = vzeroes(4);
DESCRIPTION
Overview
This package tries to help people who want to use PDL for 2D matrix
computation with lots of indexing involved. It provides a PDL
subclass so one and twodimensional piddles that are used as
vectors resp and matrices can be typed in using traditional matrix
convention.
If you want to know more about matrix operation support in PDL, you
want to read PDL::MatrixOps or PDL::Slatec.
The original pdl class refers to the first index as the first row,
the second index as the first column of a matrix. Consider
print $B = sequence(3,2)
[
[0 1 2]
[3 4 5]
]
which gives a 2x3 matrix in terms of the matrix convention, but the
constructor used (3,2). This might get more confusing when using
slices like sequence(3,2)>slice(1:2,(0)) : with traditional
matrix convention one would expect [2 4] instead of [1 2].
This subclass PDL::Matrix overloads the constructors and indexing
functions of pdls so that they are compatible with the usual matrix
convention, where the first dimension refers to the row of a
matrix. So now, the above example would be written as
print $B = PDL::Matrix>sequence(3,2) # or $B = msequence(3,2)
[
[0 1]
[2 3]
[4 5]
]
Routines like eigens or
inv can be used without any changes.
Furthermore one can construct and use vectors as n x 1 matrices
without mentioning the second index ’1’.
Implementation
PDL::Matrix works by overloading a number of PDL constructors
and methods such that first and second args (corresponding to
first and second dims of corresponding matrices) are effectively swapped.
It is not yet clear if PDL::Matrix achieves a consistent columnmajor
lookandfeel in this way.
NOTES
As of version 0.5 (rewrite by CED) the matrices are stored in the usual
way, just constructed and stringified differently. That way indexing
and everything else works the way you think it should.
FUNCTIONS
constructs an object of class PDL::Matrix which is a piddle child class.
$m = mpdl [[1,2,3],[4,5,6]];
$m = PDL::Matrix>pdl([[1,2,3],[4,5,6]]);
mzeroes, mones, msequence
constructs a PDL::Matrix object similar to the piddle constructors
zeroes, ones, sequence.
vpdl
constructs an object of class PDL::Matrix which is of matrix
dimensions (n x 1)
print $v = vpdl [0,1];
[
[0]
[1]
]
vzeroes, vones, vsequence
constructs a PDL::Matrix object with matrix dimensions (n x 1),
therefore only the first scalar argument is used.
print $v = vsequence(2);
[
[0]
[1]
]
kroneckerproduct
returns kroneckerproduct of two matrices. This is not efficiently
implemented.
det_general
returns a generalized determinant of a matrix. If the matrix is not
regular, one can specify the rank of the matrix and the corresponding
subdeterminant is returned. This is implemented using the eigens
function.
trace
returns the trace of a matrix (sum of diagonals)
BUGS AND PROBLEMS
Because we change the way piddles are constructed, not all pdl
operators may be applied to piddlematrices. The inner product is not
redefined. We might have missed some functions/methods. Internal
consistency of our approach needs yet to be established.
Because PDL::Matrix changes the way slicing behaves, it breaks many
operators, notably those in MatrixOps.
check all PDL functions, benchmarks, optimization, lots of other things ...
AUTHOR(S)
Stephan Heuel (stephan@heuel.org), Christian Soeller
(c.soeller@auckland.ac.nz).
COPYRIGHT
All rights reserved. There is no warranty. You are allowed to
redistribute this software / documentation under certain
conditions. For details, see the file COPYING in the PDL
distribution. If this file is separated from the PDL distribution, the
copyright notice should be included in the file.
perl v5.20.3  MATRIX (3)  20150812 
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