From: Daniel Carrera <dcarrera@...>
Date: 2004-01-13T00:22:03+09:00
Subject: Re: faster integer arithmetics & arbitrary precision floating number


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.


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.