Hello Luis,
probably this does the trick:
pp_def('magnover',
HandleBad => 1,
Pars => "a(n); real [o]b();",
GenericTypes => [qw(H C G E D F)],
Then in t/ufunc.t (line 106) the expected type just needs to be changed from
'cdouble' to 'double'.
Integer types will be promoted to float and complex types to their real
counterparts:
say cdouble('[1+i, 1-i, -1+i, -1-i]')->magnover->info;
say sequence($_, 4)->magnover->info for byte, long, float, double;
PDL: Double D []
PDL: Float D []
PDL: Float D []
PDL: Float D []
PDL: Double D []
Regards,
-jo
On Thu 24 Jul 2025 06:36:39 PM CEST, Luis Mochan <moc...@icf.unam.mx> wrote:
> On Wed, Jul 23, 2025 at 11:56:00AM +0000, Jörg Sommrey wrote:
> > Hello Luis,
> >
> > the results look fine when the expected types in the two
failing tests are
> > adjusted. Don't know if it would break any "real" code, maybe
"is_pdl" is
> > just too strict here.
>
> I believe there are good reasons for the qualifier float+ in the case
> of, for example, a vector of bytes: on one hand, the euclidean
> magnitude of a vector of integers is not necessarily integer: (3,4)->5
> but (1,1)->1.4142... On the other hand, the magnitude of a large
> vector of bytes may overflow a byte. Nevertheless, I expect the
> magnitude of a complex to be real, not a complex. A complex with a
> zero imaginary part works but wastes some time and space. Thus,
it would be
> ideal if one could specify both, float+ and real as qualifiers of the
> output of magnover, but that doesn't work. Is there an alternative for
> a more flexible way to determine the correct type of an output
> parameter based on that of the inputs? Meanwhile, I can simply
> take the real part of the magnitudes :)
>
> Regards,
> Luis
>
>
> >
> > t/ufunc.t:
> > is_pdl $empty->magnover, sbyte('BAD'), "bad flag gets set on empty
> > magnover";
> > is_pdl +(sequence(4)+i())->magnover, double(4.242640),
'magnover correct for
> > complex';
> >
> > Best regards,
> > -jo
> >
> >
> > On Wed 23 Jul 2025 04:52:24 AM CEST, Luis Mochan
<moc...@icf.unam.mx> wrote:
> >
> > > Hello,
> > >
> > > In some of my programs I used the code such as
> > >
> > > $abs=$cvec->abs2->sumover->sqrt;
> > >
> > > to get the magnitude of a vector $cvec. I just replaced it to
the cleaner
> > >
> > > $abs=$cvec->magnover;
> > >
> > > But then my program failed when I made the comparison
> > >
> > > if($abs > 0){...}
> > >
> > > with the message
> > >
> > > Can't compare complex numbers at lib/PDL/PP.pm line 1445.
> > >
> > > It is true that we shouldn't compare complex numbers, except for
> > > equality, but, shouldn't the magnitude of a complex vector be a real
> > > number instead of a complex number (with zero imaginary part)?
> > >
> > > I tried to fix it by replacing the qualifier 'float+' in the pp_def of
> > > magnover in Ufunc.pd by the qualifier 'real', but then the tests fail
> > > as bytes are not converted to floats.
> > >
> > > Best regards,
> > >
> > > Luis
> >
> >
> >
