Hi,
I've tried to create a PP function to calculate the Hankel matrix from a
vector. I used Inline pdlpp. Whenever I run the function, I get an out
of memory error. I tried explicit for loops as well. There is no good
example in the book or the docs where output dimensions are calculated
based on input. In this case l depends on n and m.
pp_def ('fid_to_hankel2',
Pars=>'v(n); [o]hankel(l,m)',
OtherPars=>'int ms => m',
Code => pp_line_numbers(__LINE__, q{
PDL_Indx ns = $SIZE(n);
PDL_Indx m,l;
l=ns-m+1;
printf ("size n %d , l %d , m %d\n",ns,l,m);
loop(n) %{
loop(l) %{
loop(m) %{
$hankel()=$v(n=>l+m);
printf ("n %d = l %d + m %d\n",l+m,l,m);
%}
%}
%}
}), # line_numbers
);
I know that the Hankel matrix can be created efficiently using xvals,
yvals and index.
sub hankel {
my $fid=shift;
my $rank=shift;
my $size=($rank,$fid->dim(0)-$rank+1);
my $ind=xvals($size)+yvals($size);
$fid->index($ind);
}
Nonetheless I would like to understand what's going on. Btw., that's
with pdl 2.019 on linux 64 bit. Other PP functions work alright.
Best wishes
Ingo
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