Hi Ed, I'm not sure about what should be expected for operations on real numbers that have no real answer: a complex answer or an error? (In the case of sqrt(-1) or worse, for log(-1) there is the further problem of multiple possible answers.)
Consider pdl> $i=sequence(long,10); pdl> p $i/3 [0 0 0 1 1 1 2 2 2 3] pdl> In this case, division is not promoting longs into floats. However asin(3) does promote floats into complex. sqrt(-1) isn't. So I'm still confused about what are the appropriate expectations. I'd follow your suggestion if I were sure what to request. Regards, Luis On Sat, Feb 20, 2021 at 12:52:58AM +0000, Ed . wrote: > > Is this the expected behavior? > > I’d have to say yes – the changes made by Ingo are to use <complex.h>’s > native-ish C complex-numbers support, and PDL types and code changes to > support that. The change to asin’s behaviour came for free with that. It’s > not yet fully pervasive, and I’m not 100% sure whether the new complex > behaviour should actually change to be opt-in. > > On the other hand, making it do the mathematically correct thing all the way > seems like the correct way forward! If people can try their various scripts > and extensions and see if anything breaks, and/or find things that are not > according to their expectations, it would be really helpful to report that on > here. Luis, could you open an issue on the repo and capture at least this > sqrt point? (A PR to add a failing test would be even better, and a PR with a > failing test plus code to fix the problem would be better again 😊) > > Best regards, > Ed > > From: Luis Mochan<mailto:moc...@icf.unam.mx> > Sent: 20 February 2021 00:09 > To: pdl-devel@lists.sourceforge.net<mailto:pdl-devel@lists.sourceforge.net>; > perldl<mailto:pdl-gene...@lists.sourceforge.net> > Subject: Re: [Pdl-devel] PDL 2.026_01 released to CPAN > > I installed it 026_01 (from github/master) > > > pdl> p asin(3) > 1.5707963267948966+1.7627471740390861i > > pdl> p sin(asin(3)) > 3.0000000000000004+1.7319121124709863e-16i > > Seems good, but > > pdl> p sqrt(-1) > Runtime error: Can't take sqrt of -1 at (eval 400) line 5. > > pdl> use PDL::Complex > > pdl> p sqrt(-1) > Runtime error: Can't take sqrt of -1 at (eval 416) line 5. > > pdl> p sqrt(-1+0*i) > 0 +1i > > pdl> > > Is this the expected behavior? > > Regards, > Luis > > > > On Fri, Feb 19, 2021 at 05:52:44PM -0600, Luis Mochan wrote: > > This is good news! > > Thanks! > > Luis > > > > On Fri, Feb 19, 2021 at 08:15:59PM +0000, Ed . wrote: > > > Dear PDL users, > > > > > > I’ve just uploaded PDL 2.026_01 to CPAN. It has Ingo Schmid’s “native > > > complex types” code (as tidied up a bit). Please give it a go and report > > > whether it works! Please note that now e.g. asin(3) will not return NaN, > > > but instead a complex number (which is, of course, mathematically valid). > > > > > > As Derek said, please report any issues you find to the mailing list > > > (good), or create an issue (better) or a pull request (best!) on GitHub. > > > Thanks, and Happy PDL-ing! > > > > > > Best regards, > > > Ed > > > > > > > _______________________________________________ > > > pdl-devel mailing list > > > pdl-devel@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/pdl-devel > > > > > > -- > > > > o > > W. Luis Mochán, | tel:(52)(777)329-1734 /<(*) > > Instituto de Ciencias Físicas, UNAM | fax:(52)(777)317-5388 `>/ /\ > > Av. Universidad s/n CP 62210 | (*)/\/ \ > > Cuernavaca, Morelos, México | moc...@fis.unam.mx /\_/\__/ > > GPG: 791EB9EB, C949 3F81 6D9B 1191 9A16 C2DF 5F0A C52B 791E B9EB > > > > > > _______________________________________________ > > pdl-devel mailing list > > pdl-devel@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/pdl-devel > > -- > > o > W. Luis Mochán, | tel:(52)(777)329-1734 /<(*) > Instituto de Ciencias Físicas, UNAM | fax:(52)(777)317-5388 `>/ /\ > Av. Universidad s/n CP 62210 | (*)/\/ \ > Cuernavaca, Morelos, México | moc...@fis.unam.mx /\_/\__/ > GPG: 791EB9EB, C949 3F81 6D9B 1191 9A16 C2DF 5F0A C52B 791E B9EB > > > _______________________________________________ > pdl-devel mailing list > pdl-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/pdl-devel > -- o W. Luis Mochán, | tel:(52)(777)329-1734 /<(*) Instituto de Ciencias Físicas, UNAM | fax:(52)(777)317-5388 `>/ /\ Av. Universidad s/n CP 62210 | (*)/\/ \ Cuernavaca, Morelos, México | moc...@fis.unam.mx /\_/\__/ GPG: 791EB9EB, C949 3F81 6D9B 1191 9A16 C2DF 5F0A C52B 791E B9EB _______________________________________________ pdl-devel mailing list pdl-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/pdl-devel
