Hi Ed, thanks for picking this up! I am really really bad at housekeeping and with multi-developer git, I'm sorry for the mess I've left you to deal with. When I saw you released the new version, I was actually considering giving it a push. Now I am really grateful you beat me to it ! ;)
There was still the issue of build failure on windows with bad values and either use NaNs as bad on or off. Have you managed to root that out? I've run out of steam on this. It was really just one combination that caused the failure. With regard to expected behaviour, that is difficult really, as there often is no general answer. I guess I would advise to be conservative so that existing real-valued code behaves as much the same way as it ever did. I figure that this is probably quite difficult to do rigorously. As some veteran developers for sure know is that there is an implicit promotion of types to double, which is still in place. I think it is somewhere hidden in PP, I think. Other parts of the code implicitly or explicitly rely on this, if I remember correctly. That leads to the odd cases when a function is not defined for complex numbers, the argument is cast to double (which is the real part) and then silently used in the function. To the point, the desired behaviour of implicit casts is now even more relevant and has become non-trivial then it used to be so far. Anyone remembering the 64-bit integer to double loss of precision discussion? Best Ingo On 2/20/2021 2:20 AM, Ed . wrote: > > For sqrt with real numbers, there's already multiple possible answers! > So this is not adding any additional problems. > > > > For log, it’s probably most pragmatic to have an additional > function, which already exists in PDL::Complex. Question: does this > new “native” complex support mean PDL::Complex should change / be > simplified? Also, are you saying that you consider the behaviour of > promoting floats/doubles into their complex counterparts is wrong? > > > > Best regards, > > Ed > > > > *From: *Luis Mochan <mailto:moc...@icf.unam.mx> > *Sent: *20 February 2021 01:08 > *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 > > > > > 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 <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 > <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 > <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 > <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 > <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 > <https://lists.sourceforge.net/lists/listinfo/pdl-devel> > > > > > > _______________________________________________ > pdl-devel mailing list > pdl-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/pdl-devel
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