From: Robert Klemme <bob.news@...>
Date: 2004-01-13T01:31:40+09:00
Subject: Re: faster integer arithmetics & arbitrary precision floating number


"Daniel Carrera" <dcarrera@math.umd.edu> schrieb im Newsbeitrag
news:20040112152151.GA846@math.umd.edu...
>
> One idea would be to make a "FastInt" class that stores inegers as
regular C
> int's.  It could work like this:
>
> int1 = FastInt.new(1073741823)
> int2 = FastInt.new(073741824)
>
> 1000000.times{ int1 + int2 }
>
> So addition would be done in C, which would be faster.
>
> Notice: If you create the integers about as often as you add them, the
> conversion from Ruby to C and back would more than compensate for any
gains
> from C (I suspect).
>
> I would expec that this:
>
> 1000000.times do
>     int1 = FastInt.new(1073741823)
>     int2 = FastInt.new(073741824)
>     int1 + int2
> end
>
>
> would be even slower.

Of course you would define FastInt#add which adds something to the current
instance, removing the overhead of object creation.

Cheers

    robert

>
>
> Cheers,
> Daniel.
>
>
> On Tue, Jan 13, 2004 at 12:09:53AM +0900, David Garamond wrote:
> > 1. Is there a way in Ruby to speed up 32bit integer arithmetics (only
> > involving numbers & sums up to 2^32-1)? I want to use Ruby for
> > summarizing network traffic logs, but it's pathetically slow compared
to
> > Perl:
> >
> > $ time ruby -e'1000000.times{1073741823+1073741824}'
> >
> > real    0m23.693s
> > user    0m5.720s
> > sys     0m0.610s
> > $ time perl -e'for(1..1000000){1073741823+1073741824}'
> >
> > real    0m1.142s
> > user    0m0.320s
> > sys     0m0.050s
> >
> > since 2**30 is already in the Bignum range.
> >
> > 2. Doing arbitrary integer math is already very convenient in Ruby
> > because of its automatic conversion. But Ruby still doesn't do
seamless
> > conversion to arbitrary floating point numbers:
> >
> > $ irb
> > irb(main):001:0> 0.00000000000000001
> > => 1.0e-17
> > irb(main):002:0> 0.000000000000000001
> > => 0.0
> >
> > Any chance Ruby will do this in the future? Or perhaps in the nearer
> > future, include an arbitrary floating number package in its
distribution
> > (is there any? GMP is GPL so it potentially a problem license-wise).
> >
> > -- 
> > dave
> >
>
> -- 
> Daniel Carrera | No trees were harmed in the generation of this  e-mail.
> PhD student.   | A significant number of electrons were, however,
severely
> Math Dept. UMD | inconvenienced.
>
>
>