Re: [bug-gawk] GAWK 4.1: Division with Arbitrary Precision Integers

[Manuel Collado]

El 06/08/2013 22:07, Katherine Wasserman escribió:
> Hi Andy
>
> > Perhaps something like div(numerator, denominator, result) where
> > the result will be an array with a "quot" element and a "rem"
> > element.  I don't think it's possible to have a function that returns
> > an array, but I'm not certain...
>
> Maybe div() could just return the quotient and an optional third
> argument could return the remainder.  This would save the extra steps
> needed to pull apart an array and most often throw out the remainder
> portion.

Yes. This seems the simplest approach.


> Also the '%' operator seems to work ok with bignums so there
> already is a useable remainder function.
>
> Thanks,
> -Katie
>
> At 02:08 PM 8/6/2013, Andrew J. Schorr wrote:
> > Hi,
> >
> > On Tue, Aug 06, 2013 at 01:01:40AM -0400, Katherine Wasserman wrote:
> > > There is currently no way to preform division of arbitrary precision integers 
> > > in gawk, the system will always convert numbers to floating point when using 
> > > the '/' operator.
> > >
> > > Per Aharon , there appear to be at least two ways around this:
> > >
> > > 1) change the semantics of the '/' operator.
> >
> > I don't think we could change the behavior of the '/' operator unless we
> > introduced a new option to select this behavior.  That doesn't sound
> > workable to me...
> >
> > > 2) introduce a new function for integer division.
> > >
> > > I think that the later is both cleaner and useful as a function even without 
> > > the MPFR/MP extensions loaded.
> >
> > I think this is the right solution.  There is a "div" function in
> > ISO C that does what we want:
> >
> > http://pubs.opengroup.org/onlinepubs/9699919799/functions/div.html

BTW, the Pascal language (and some derivatives) has always had two division 
operators for integers:

  integer / integer -> float
  integer div integer -> integer

So "div" seems a common name for the integer division operator/function.

> > Perhaps something like div(numerator, denominator, result) where
> > the result will be an array with a "quot" element and a "rem"
> > element.  I don't think it's possible to have a function that returns
> > an array, but I'm not certain...
> >
> > Regards,
> > Andy

Regards,

--
Manuel Collado - http://lml.ls.fi.upm.es/~mcollado