> >> If I try to call this function with
> >>
> >> my $a = testfunc( pdl(1,2,3) );
> >>
> >> the perl simply croaks with "Out of memory!". Calling this
> >> function with
> >>
> >> testfunc( pdl(1,2,3), my $a );
> >>
> >> doesn't crash immediately, but the output piddle is n-by-1 NOT n-
> >> by-2. I now
> >> realize that in the definition above, I'm not asking for an
> >> n-by-2, piddle,
> >> rather the "2" is a name for that dimension that can have an
> >> arbitrary size. I
> >> discovered that I can make that function work my adding another
> >> key to pp_def():
> >>
> >> RedoDimsCode => '$SIZE(1) = 1; $SIZE(2) = 2;',
> >>
> >> This works in the simplest case, but not completely. If I define
> >> an input piddle
> >> to be n-by-2 this way, and pass in an n-by-1 piddle instead of n-
> >> by-2, nothing
> >> complains. Is this the correct behavior? Is "RedoDimsCode" the
> >> right way to do
> >> this? Should PP treat numerical dimensions as constant sizes
> >> instead of just
> >> another named dimension? Thanks.
> > On 4/23/2011 7:00 PM, Dima Kogan wrote:
> >> Hi. I'm using PP to define a function that takes a piddle with some
> >> constant dimensions, and I'm having a bit of trouble.
> >>
> >> The function is defined as:
> >>
> >> pp_def("testfunc",
> >> Pars => ' a(n,1); [o]b(n,2);',
> >> Code => ''
> >> );
> >
> > I looked at the various signatures in the PDL
> > source and found the following usage:
> >
> > pp_def("testfunc",
> > Pars => ' a(n,m=1); [o]b(n,p=2);',
> > Code => ''
> > );
> >
> > Does that work better? --Chris
> >
>
> On Mon, 25 Apr 2011 17:30:31 -0600
> Craig DeForest <[email protected]> wrote:
>
> Ah. Thanks, Chris -- I meant to respond to Dima before but it fell
> off the radar.
>
> One other point: Dima, you probably don't want to force your input
> to have two input dimensions and
> also be n-by-1: in that case your algorithm probably really wants
> just a single active dimension. I suggest
> trying a signature like
>
> Pars => 'a(n); [o]b(n,p=2);',
>
> (as Chris suggested with the output size). Then your operator
> becomes a sort of inverse-collapse operation.
> Depending on how you think about the output (is it a collection of 2
> n- tuples? Or is it more naturally a
> collection of n 2-tuples?) you also might want to rearrange the
> output dimensions to (p=2,n).
Aha. That appears to be the correct syntax. Thanks much for that. Is there a lot
of knowledge of PP left on this list, or is reading the source the main method
for figuring it out these days? I've seen the following undocumented flags in
various PP definitions: c,a,phys. Anybody knows what those do?
In any case there's enough documentation for me to have completed a
first cut to the OpenCV bindings:
https://github.com/dkogan/PDL-OpenCV
These bindings appear to work with some caveats (all piddles must be pre-made
when calling the functions, some extra data copying may be done (as per my
previous post), etc). Any testing and/or comments are welcome.
Thanks!
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