Henry:

 a=:!19
  3!:0 a
8 NB. floating point
  b=:!x:19
  3!:0 b
64 NB. extended integer

So in principle x: 4*a is rational, not an integer.

There is a difference between J504 and J601.  J601 gives your result
below, while J504 gives
  x: 4*a
486580401635328000

However, in J601
  0j0 ": 4*a
486580401635328000

As I have learned from Roger by asking similar questions (e.g. why is the
real part of a complex number complex and not real), one should not be
conditioning ones code on the internal types.

Best wishes,

John




Henry Rich wrote:
> Piddling around with x: I find:
>
>    a =. !19
>    3!:3 a
> e1000000
> 08000000
> 01000000
> 00000000
> 00906830
> b9027b43
>    3!:3 a*4
> e1000000
> 08000000
> 01000000
> 00000000
> 00906830
> b9029b43
>    x: a
> 121645100408832000
>    x: a * 4
> 33437550590372456995572480375r68719476736
>
> I don't see why this last result is a fraction, since the exponent
> looks like about 2^60.
>
> Henry Rich
>
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
>


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