Re: [Bug-apl] Complex number display

[Frederick H. Pitts]

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
> >>          
> >>          
> >>
> >>
> >
> >
> >
>

COMPLEX.tar.gz
Description: application/compressed-tar