Re: [Bug-apl] Rational Numbers

[Ala'a Mohammad]

Hi Jürgen,

Thanks go to you for the prompt response. I do really appreciate it.

Regards,

Ala'a

On Sat, Aug 12, 2017 at 12:26 AM, Juergen Sauermann
<address@hidden> wrote:
> Hi Ala'a,
>
> thanks, fixed in SVN 993.
>
> /// Jürgen
>
>
> On 08/11/2017 03:22 PM, Ala'a Mohammad wrote:
>
> Hi Jürgen,
>
> I was playing with experimental support for rational numbers and found
> that result was converted to float while using dyadic maximum,
> minimum, even though I did not use the monadic +
>
>         (1÷3) ⌈ (3÷4)
> 0.75
>
>         (1÷3) ⌊ (3÷4)
> 0.3333333333
>
> Is this the intended display?
>
> Also by accident, I was playing with the support and the strange
> display of the following occurred
>
>         ÷¯1÷3
> 3÷18446744073709551615
>
> Entering the above result gives another number
>
>         3÷18446744073709551615
> 1.626303259E¯19
>
> The positive case works better (even though I had expected one digit
> display only '3'), but somehow the neg mess-up the display
>
>         ÷1÷3
> 3÷1
>
> Regards,
>
> Ala'a
>
> On Sun, Jul 23, 2017 at 5:28 PM, Juergen Sauermann
> <address@hidden> wrote:
>
> Hi Elias,
>
> the format bug is fixed in SVN 983.
>
> Rational numbers are exact, they are stored as a 64 bit numerator and a 64
> bit denominator.
> You can convert a rational to a float with monadic +:
>
>       ⎕PS←1 0   ⍝ display quotients
>       2÷3
> 2÷3
>       +2÷3
> 0.6666666667
>
> Normally monadic + is not needed because conversion to double happens
> automatically where needed.
>
> /// Jürgen
>
>
> On 07/21/2017 06:19 AM, Elias Mårtenson wrote:
>
> There is an error in the rational code:
>
> In Archive.cc, line 218, the snprintf format is wrong. %lld is used, while
> the types of the arguments are actually "long". Thus, "%lld÷%lld" should be
> "%ld÷%ld" instead.
>
> On 21 July 2017 at 12:06, Elias Mårtenson <address@hidden> wrote:
>
> I haven't looked at this yet, but is this purely a display feature, or is
> it a full implementation of rational numbers?
>
> In other words, is the result of 1÷3 exact? And if so, how do I convert a
> rational number into a floating-point number?
>
> Regards,
> Elias
>
> On 21 July 2017 at 00:05, Juergen Sauermann
> <address@hidden> wrote:
>
> Hi,
>
> coming back to a proposal from Elias, I have added (experimental) support
> for rational numbers in GNU APL. SVN 982.
>
> It has to be enabled explicitly:
>
> ./configure RATIONAL_NUMBERS_WANTED=yes
>
> In APL you can display rational numbers by setting ⎕PS[1]:
>
>       ⎕PS←0 22
>       2÷3
> ╔════════════╗
> ║0.6666666667║
> ╚════════════╝
>       ⎕PS←1 22
>       2÷3
> ╔═══╗
> ║2÷3║
> ╚═══╝
>
> (The second item in ⎕PS is a boxing style as in the ]BOXING command).
>
> Best Regards,
> Jürgen
>
>
>