bignum 0.22

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Subject

Author

Date

bignum 0.22

gamo

07-04-2007

Sisyphus

gamo

gamo

Mumia W.

gamo

xhoster

Sisyphus

Mumia W.

gamo

Mumia W.

Sisyphus

xhoster

Sisyphus

José Luis Pérez...

Posted by gamo on July 5, 2007, 12:02 pm

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On Thu, 5 Jul 2007, Mumia W. wrote:

> You can set the "accuracy" of the bignum module. Read "perldoc bignum"

> BTW, if you make fact() recursive and use the Memoize module, you can get a

> speed improvement--a /substantial/ speed improvement :-)

Thanks all of you.
This trick really really improve speed.

But if there is no previous knowledge that all numbers will be
integers I can not fix the precision or accuracy.

Cheers

Posted by xhoster on July 5, 2007, 12:38 pm

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> On Thu, 5 Jul 2007, Mumia W. wrote:

> > You can set the "accuracy" of the bignum module. Read "perldoc bignum"

> >

> > BTW, if you make fact() recursive and use the Memoize module, you can

> > get a speed improvement--a /substantial/ speed improvement :-)

> >

> Thanks all of you.

> This trick really really improve speed.

> But if there is no previous knowledge that all numbers will be

> integers

Aren't Catalan numbers only defined on integers?

> I can not fix the precision or accuracy.

Choosing to leave the defaults in place is still a choice, and you should
understand what the consequences of that choice are. It is not for the
accuracy and precision to be infinite. They are still limited through
some confusing fall-back method.

Xho

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Posted by Sisyphus on July 5, 2007, 11:08 pm

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> On 07/05/2007 04:36 AM, gamo wrote:

>> On Thu, 5 Jul 2007, Sisyphus wrote:

>>>> Hello

>>>>

>>>> I found a problem related with calculating Catalan's numbers

>>>>

>>> What is the problem ? (I don't see it.)

>>>

>>> Cheers,

>>> Rob

>> The problem is that this output lacks precision aparently

>> 216489185503133990863274261791925599831200000000000000000000

>> 853702637172735926234421145556838686126800000000000000000000

>> 3366939372774715522158184331074634818182000000000000000000000

>> [...]

> You can set the "accuracy" of the bignum module. Read "perldoc bignum"

Oh, yes ... I should've realised.

Is that a bug in bignum ? I didn't see it documented anywhere that there was
a default "accuracy" set.
The same issue does not arise if you explicitly 'use Math::BigInt;'.

Cheers,
Rob

Posted by Mumia W. on July 6, 2007, 2:04 am

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On 07/05/2007 10:08 PM, Sisyphus wrote:

>> On 07/05/2007 04:36 AM, gamo wrote:

>>> On Thu, 5 Jul 2007, Sisyphus wrote:

>>>

>>>>> Hello

>>>>>

>>>>> I found a problem related with calculating Catalan's numbers

>>>>>

>>>> What is the problem ? (I don't see it.)

>>>>

>>>> Cheers,

>>>> Rob

>>>

>>> The problem is that this output lacks precision aparently

>>>

>>> 216489185503133990863274261791925599831200000000000000000000

>>> 853702637172735926234421145556838686126800000000000000000000

>>> 3366939372774715522158184331074634818182000000000000000000000

>>> [...]

>> You can set the "accuracy" of the bignum module. Read "perldoc bignum"

> Oh, yes ... I should've realised.

> Is that a bug in bignum ? I didn't see it documented anywhere that there

> was a default "accuracy" set.

> The same issue does not arise if you explicitly 'use Math::BigInt;'.

> Cheers,

> Rob

Yes, I also noticed that Math::BigInt (or "bigint") works right out of
the box.

Evidently "bignum" has more to do and is more complicated, and
consequently, has more bugs. In this case, I don't know if the bug is in
the documentation or code; however, I think that the default accuracy
should be given in the POD.

Nonetheless, it can be queried by calling Math::BigFloat->accuracy().

Gamo, why did you choose bignum rather than bigint?

Posted by gamo on July 6, 2007, 4:53 am

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On Fri, 6 Jul 2007, Mumia W. wrote:

> On 07/05/2007 10:08 PM, Sisyphus wrote:

> >

> > > On 07/05/2007 04:36 AM, gamo wrote:

> > > > On Thu, 5 Jul 2007, Sisyphus wrote:

> > > >

> > > > > > Hello

> > > > > >

> > > > > > I found a problem related with calculating Catalan's numbers

> > > > > >

> > > > > What is the problem ? (I don't see it.)

> > > > >

> > > > > Cheers,

> > > > > Rob

> > > >

> > > > The problem is that this output lacks precision aparently

> > > >

> > > > 216489185503133990863274261791925599831200000000000000000000

> > > > 853702637172735926234421145556838686126800000000000000000000

> > > > 3366939372774715522158184331074634818182000000000000000000000

> > > > [...]

> > >

> > > You can set the "accuracy" of the bignum module. Read "perldoc bignum"

> > >

> >

> > Oh, yes ... I should've realised.

> >

> > Is that a bug in bignum ? I didn't see it documented anywhere that there was

> > a default "accuracy" set.

> > The same issue does not arise if you explicitly 'use Math::BigInt;'.

> >

> > Cheers,

> > Rob

> Yes, I also noticed that Math::BigInt (or "bigint") works right out of the

> box.

> Evidently "bignum" has more to do and is more complicated, and consequently,

> has more bugs. In this case, I don't know if the bug is in the documentation

> or code; however, I think that the default accuracy should be given in the

> POD.

> Nonetheless, it can be queried by calling Math::BigFloat->accuracy().

> Gamo, why did you choose bignum rather than bigint?

Because it's simple to use. It overloads any operation.
Fire and forget. No OOP nor especial commands.
If I need to use only BigInt, I'll check GMP::Mpz or Math::PARI, too.
PARI is another kind of animal, because it does functions.
Best regards,

--
http://www.telecable.es/personales/gamo/
perl -e 'print 111_111_111**2,"\n";'

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