PDL::Matrix (3)
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NAME
PDL::Matrix -- a convenience matrix class for column-major accessVERSION
This document refers to version PDL::Matrix 0.5 of PDL::MatrixSYNOPSIS
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 useIf you want to know more about matrix operation support in
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 ofNOTES
As of version 0.5 (rewrite byFUNCTIONS
mpdl, PDL::Matrix::pdl
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 piddle-matrices. 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.