Re: [Bug-apl] Complex number display

[Juergen Sauermann]

Hi Fred,

thanks, fixed in SVN 280.

/// Jürgen


On 05/21/2014 03:28 AM, Frederick H. Pitts wrote:
> Hello Juergen, Elias,
>
>         I think there are still three flies in the "complex number display"
> ointment.  Please see the attached tar file containing a APL test file
> and a log file generated from it using GnuAPL svn 279.  Only one of the
> 4 complex numbers entered in polar form and that have a zero real part
> is displayed with a 0 for the real part.  The remaining 3 numbers
> display with a real part having a E¯16 scale factor.  For these 3
> numbers, the real part magnitude is definitely 10 orders of magnitude
> less than the imaginary part magnitude and should display with a 0 for
> the real part.
>
> Regards,
>
> Fred
>
> On Tue, 2014-05-20 at 18:09 +0200, Juergen Sauermann wrote:
> > Hi Fred, Elias,
> >
> > fixed in SVN 279.
> >
> > I dared to print the (non-zero) imaginary part even if the standard
> > tells otherwise.
> >
> > /// Jürgen
> >
> >
> > On 05/20/2014 07:35 AM, Frederick H. Pitts wrote:
> > > Elias,
> > >
> > >         The part before the "Then:" states the obvious.  Numeric output
> > > conversion converts numbers in internal format (implementation-defined))
> > > to external literal decimal format.
> > >
> > >         The part after the "Then:" is totally bogus.  What is the point of
> > > performing complex number calculations and then summarily throwing away
> > > the imaginary part?  The imaginary part could be the part the user is
> > > interested in.
> > >
> > >         Sincerely, I do not see anything here that legitimately contradicts the
> > > descriptions cited in the IBM APL2 Language Reference.  The IBM document
> > > says 1) display the real part as 0 if the real part magnitude is ⎕PP
> > > orders of magnitude less than the imaginary part magnitude and 2)
> > > suppress the display imaginary part if its magnitude is ⎕PP orders of
> > > magnitude less than the real part.  The exception is when ⎕PP is at
> > > maximum; then both parts are displayed at full precision.
> > >
> > > Regards,
> > >
> > > Fred
> > >
> > > On Tue, 2014-05-20 at 12:47 +0800, Elias Mårtenson wrote:
> > > > ISO/IEC 13751:2000 seems to give an implementation lots of flexibility
> > > > here.
> > > >
> > > >
> > > > I'm honestly not sure how to interpret this. Section 15.2.2 says:
> > > >
> > > >
> > > >           Informal Description: Numeric output conversion converts
> > > >           numeric values represented as numbers—numeric quantities whose
> > > >           format is implementation-defined—into the same numeric
> > > >           quantities represented in decimal notation as lists of
> > > >           characters.
> > > >
> > > >
> > > > Then:
> > > >
> > > >
> > > >           Note: Any imaginary-part of the numeric input to
> > > >           Numeric-Output-Conversion is simply ignored; only the
> > > >           real-part of a complex-number is used.
> > > >
> > > >
> > > > Regards,
> > > > Elias
> > > >
> > > >
> > > > On 20 May 2014 12:24, Frederick H. Pitts <address@hidden>
> > > > wrote:
> > > >           Juergen,
> > > >           
> > > >                   Under "Display of Complex Numbers:" on page 13 of the
> > > >           "APL2
> > > >           Programming: Language reference", the document says:
> > > >           
> > > >                   "In J notation, the real or imaginary part is not
> > > >           displayed if it is
> > > >           less than the other by more than ⎕PP orders of magnitude
> > > >           (unless ⎕PP is
> > > >           at its maximum)".
> > > >           
> > > >                   In SVN 268, neither of the presented examples work.
> > > >            The smaller
> > > >           magnitude part is not zeroed if its the real part or
> > > >           suppressed if its
> > > >           the imaginary part.
> > > >           
> > > >                   In addition, complex numbers entered in polar notation
> > > >           as described at
> > > >           the top page 12 do not display correctly per the description
> > > >           on page 13.
> > > >           1D90 and 1R1.5707963267948965 should display as 0J1 assuming
> > > >           ⎕PP is less
> > > >           than maximum.  Currently the real part is displayed as some
> > > >           number times
> > > >           10 to the -16 power, i.e. zero for all intents and purposes.
> > > >           
> > > >           Regards,
> > > >           
> > > >           Fred
> > > >           Retired Chemical Engineer
> > > >           
> > > >