>
> I'm a little confuse with PDL::Matrix...
>
> Is the code in "Work in Progress"? I see in the
> PDL manpages (on the web site) that not all the
> operators are redefined...
The PDL::Matrix class is just a wrapper class
that lets you use column-major access in PDL.
However because all the functionality is not
"wrapped" it may be easier to calculate directly
and handle data ordering yourself where needed.
> Here is my problem: I have to use SVD to compress
> a quite huge matrix (~5000 columns), so I'm using
> SVD on R, but I want to implement this in my perl
> interface. What I want is to pass my matrix and
> get back another matrix (not a piddle) but:
perldl> help svd
> I do not understand how the matrix is
> saved: by columns (I suppose) or by lines,
> still mdims seems to not work... ("" print
> $datasAdjust->mdims() "" don't write anything
> on the terminal...)
PDL saves data like C arrays as blocks of memory in
row-major order (FORTRAN and usual matrix algebra
index conventions are column-major).
> I don't know how to scale the matrix (centering
> is sufficiant, no need to realy scale)
For a quick intro and overview to PDL try looking
at:
perldl> help PDL::Impatient
>
> I don't know how to make an inner product (The
> manpages say that they is not yet...)
perldl> apropos inner
Will give you a list of the PDL innerproduct functions.
Then you can use the 'help' command in the perldl shell.
> I don't know how to manipulate the matrix by hand
> or to get the informations back to my own format
> (not a piddle)
Take a look at the 'list', 'set', and 'at' functions
PDL.
> So, is this package usable, or I have to find
> another way (perhaps use the GSL library whith
> binding from perl...?) If it is usable, where
> can I get some tutorial or documentation other
> than the manpages that give me the tricks I need?
I recommend the interactive perldl shell to explore
and try things out. In the shell, "?" is a synonym
for "help" and "??" is a synonym for "apropos".
> regards,
> Laurent.
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