Re: [Bug-apl] Complex number display

[Juergen Sauermann]

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
> >          
> >