GMP Library and POWER

**Keith Thompson** · Sep 30 '08, 05:35 PM

Re: GMP Library and POWER

calimero22@free mail.it writes:

I'musing the GMP Libraries Mathematics.
>
I need to calculate 123456789876543 21.123456787655 4456 ^
987654321234455 6676.676767676
>
How can i do ?
The two variables are type MPF.

Your question isn't about the C language.

I'm sure GMP includes extensive documentation. Did it not answer your
question?

--
Keith Thompson (The_Other_Keit h) kst-u@mib.org <http://www.ghoti.net/~kst>
Nokia
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"

**calimero22@freemail.it** · Sep 30 '08, 05:35 PM

Re: GMP Library and POWER

On 30 Set, 19:27, Keith Thompson <ks...@mib.orgw rote:

calimer...@free mail.it writes:

I'musing the GMP Libraries Mathematics.

>

I need to calculate 123456789876543 21.123456787655 4456 ^
987654321234455 6676.676767676

>

How can i do ?
The two variables are type MPF.

>
Your question isn't about the C language.
>
I'm sure GMP includes extensive documentation. Did it not answer your
question?
>
--
Keith Thompson (The_Other_Keit h) ks...@mib.org <http://www.ghoti.net/~kst>
Nokia
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"

Ok. scuse me.
The documentation doesn't report then solution.
Thanks adn Scuse me.

**jameskuyper@verizon.net** · Sep 30 '08, 05:45 PM

Re: GMP Library and POWER

calimer...@free mail.it wrote:

Hi
I'musing the GMP Libraries Mathematics.
>
I need to calculate 123456789876543 21.123456787655 4456 ^
987654321234455 6676.676767676
>
How can i do ?
The two variables are type MPF

The GMP libraries are off-topic in this group, and I know nothing
about them. However, I would like to ask you about the problem you
want to solve. There's strong hints that the numbers you've given are
just examples. However, your example indicates that you want to raise
a fairly large number with LOTS of significant digits to the power of
another very large number which also has LOTS of significant digits.
If the required number of significant digits in the answer must be
comparable, then this is an exceedingly difficult problem. I consider
it extremely unlikely (but admittedly not impossible) that you
actually have a good reason for performing this calculation. Could you
please explain why you want to calculate it? I strongly suspect
someone will be able to point out a way to rearrange your question so
that the information you really need can be found out much more
accurately than the answer to your original question.

**calimero22@freemail.it** · Sep 30 '08, 06:05 PM

Re: GMP Library and POWER

On 30 Set, 19:36, jameskuy...@ver izon.net wrote:

calimer...@free mail.it wrote:

Hi
I'musing the GMP Libraries Mathematics.

>

I need to calculate 123456789876543 21.123456787655 4456 ^
987654321234455 6676.676767676

>

How can i do ?
The two variables are type MPF

>
The GMP libraries are off-topic in this group, and I know nothing
about them. However, I would like to ask you about the problem you
want to solve. There's strong hints that the numbers you've given are
just examples. However, your example indicates that you want to raise
a fairly large number with LOTS of significant digits to the power of
another very large number which also has LOTS of significant digits.
If the required number of significant digits in the answer must be
comparable, then this is an exceedingly difficult problem. I consider
it extremely unlikely (but admittedly not impossible) that you
actually have a good reason for performing this calculation. Could you
please explain why you want to calculate it? I strongly suspect
someone will be able to point out a way to rearrange your question so
that the information you really need can be found out much more
accurately than the answer to your original question.

Exact
i must find the logarithm and i need to calculate a great float number
power to a great float number.
Is there a discussion group about GMP library ?

Thanks and scuse me again.
Giovanni

**Eric Sosman** · Sep 30 '08, 06:15 PM

Re: GMP Library and POWER

calimero22@free mail.it wrote:

Hi
I'musing the GMP Libraries Mathematics.
>
I need to calculate 123456789876543 21.123456787655 4456 ^
987654321234455 6676.676767676
>
How can i do ?
The two variables are type MPF.

As Keith Thompson points out, your question isn't about C but
about the GMP product.

He might also have pointed out that you don't have enough money
to afford the answer (assuming you mean ^ to signify exponentiation) .
The result will have about 1.6E20 decimal digits in the integer part
alone, roughly 5.3E20 bits or 66E18 eight-bit bytes in ordinary
positional notation. Sixty-six exabytes, or sixty-six thousand
petabytes, or sixty-six million terabytes. I hope you've got plenty
of RAM, and a machine able to address it all (note that a 64-bit
address is too small).

--
Eric.Sosman@sun .com

**Flash Gordon** · Sep 30 '08, 07:05 PM

Re: GMP Library and POWER

calimero22@free mail.it wrote, On 30/09/08 19:01:

On 30 Set, 19:36, jameskuy...@ver izon.net wrote:

>calimer...@fre email.it wrote:

>>Hi
>>I'musing the GMP Libraries Mathematics.
>>I need to calculate 123456789876543 21.123456787655 4456 ^
>>9876543212344 556676.67676767 6
>>How can i do ?
>>The two variables are type MPF

Exact
i must find the logarithm

Using a logarithm function woud probably be a better idea!

and i need to calculate a great float number
power to a great float number.

Hmm. I suspect your algorithm needs some work.

Is there a discussion group about GMP library ?

Yes, and there are links to them on the GMP library web site! See

The GNU MP Bignum Library

http://gmplib.org/

--
Flash Gordon
If spamming me sent it to smap@spam.cause way.com
If emailing me use my reply-to address
See the comp.lang.c Wiki hosted by me at http://clc-wiki.net/

**Antoninus Twink** · Sep 30 '08, 07:15 PM

Re: GMP Library and POWER

On 30 Sep 2008 at 18:01, calimero22@free mail.it wrote:

i must find the logarithm and i need to calculate a great float number
power to a great float number.

You can't do it out-of-the-box using GMP. For example, there's no way of
calculating e to some floating-point power. You'll need to write your
own exponential and logarithm functions using power series expansions or
whatever your favorite numerical method is.

Is there a discussion group about GMP library ?

This is an excellent place to ask about GMP. You'll annoy the local
grumps, who want to change the character of this group from a C group to
an ISO-C group, but just ignore them - they'll refuse to give you any
useful help anyway.

**Trent Josephsen** · Sep 30 '08, 07:45 PM

Re: GMP Library and POWER

Eric Sosman wrote:

calimero22@free mail.it wrote:

>Hi
>I'musing the GMP Libraries Mathematics.
>>
>I need to calculate 123456789876543 21.123456787655 4456 ^
>98765432123445 56676.676767676
>>
>How can i do ?
>The two variables are type MPF.

>
As Keith Thompson points out, your question isn't about C but
about the GMP product.
>
He might also have pointed out that you don't have enough money
to afford the answer (assuming you mean ^ to signify exponentiation) .
The result will have about 1.6E20 decimal digits in the integer part
alone, roughly 5.3E20 bits or 66E18 eight-bit bytes in ordinary
positional notation. Sixty-six exabytes, or sixty-six thousand
petabytes, or sixty-six million terabytes. I hope you've got plenty
of RAM, and a machine able to address it all (note that a 64-bit
address is too small).
>

[OT]
Not to mention that if you can write two digits per second, it would
take about 252 billion years to write the answer out longhand!

You did mention the word "logarithm" . I presumed when I read it that
you meant "algorithm" , but if you only need to find a /logarithm/ of
such a number, i.e.

log(12345678987 654321.12345678 76554456 ** 987654321234455 6676.676767676)

where ** represents exponentiation, you want to multiply the exponent by
the logarithm of the base. That is,

log (b ** e) == e * log (b)

which makes it possible to calculate the logarithms of very large powers
of numbers without calculating the number itself.

**jameskuyper@verizon.net** · Sep 30 '08, 09:05 PM

Re: GMP Library and POWER

calimer...@free mail.it wrote:

On 30 Set, 19:36, jameskuy...@ver izon.net wrote:

calimer...@free mail.it wrote:

Hi
I'musing the GMP Libraries Mathematics.

I need to calculate ï¿½123456789876 54321.123456787 6554456 ï¿½^
987654321234455 6676.676767676

How can i do ?
The two variables are type MPF

The GMP libraries are off-topic in this group, and I know nothing
about them. However, I would like to ask you about the problem you
want to solve. There's strong hints that the numbers you've given are
just examples. However, your example indicates that you want to raise
a fairly large number with LOTS of significant digits to the power of
another very large number which also has LOTS of significant digits.
If the required number of significant digits in the answer must be
comparable, then this is an exceedingly difficult problem. I consider
it extremely unlikely (but admittedly not impossible) that you
actually have a good reason for performing this calculation. Could you
please explain why you want to calculate it? I strongly suspect
someone will be able to point out a way to rearrange your question so
that the information you really need can be found out much more
accurately than the answer to your original question.

>
>
>
>
Exact
i must find the logarithm and i need to calculate a great float number
power to a great float number.

It's a lot easier to find the logarithm of that number than it is to
calculate the number itself. In C terms,

long double log_number = logl(1234567898 7654321.1234567 876554456L) *
987654321234455 6676.676767676L ;

I have no idea how to convert that into GMP terms.

You can even perform that calculation in C and get a fairly large
number of significant digits (though on a typical implementation even
long double won't have as many significant digits as you need.

Is there a discussion group about GMP library ?

Sorry, I don't know.

**Nick Keighley** · Oct 1 '08, 08:25 AM

Re: GMP Library and POWER

On 30 Sep, 19:09, Eric Sosman <Eric.Sos...@su n.comwrote:

calimer...@free mail.it wrote:

Hi
I'musing the GMP Libraries Mathematics.

>

I need to calculate 123456789876543 21.123456787655 4456 ^
987654321234455 6676.676767676

>

How can i do ?
The two variables are type MPF.

>
As Keith Thompson points out, your question isn't about C but
about the GMP product.
>
He might also have pointed out that you don't have enough money
to afford the answer (assuming you mean ^ to signify exponentiation) .
The result will have about 1.6E20 decimal digits in the integer part
alone, roughly 5.3E20 bits or 66E18 eight-bit bytes in ordinary
positional notation. Sixty-six exabytes, or sixty-six thousand
petabytes, or sixty-six million terabytes. I hope you've got plenty
of RAM, and a machine able to address it all (note that a 64-bit
address is too small).

isn't it worse than that?

log(a ^ b) = log(a) * b

log(a) /= 16
log(a) * b /= 10^20

so log(a ^ b) has 20 decimal places...

(where log is log base 10, ^ is exponentiation
/= is approximatly)

I must have done something wrong here...

--
Nick Keighley

**Eric Sosman** · Oct 1 '08, 12:35 PM

Re: GMP Library and POWER

Nick Keighley wrote:

On 30 Sep, 19:09, Eric Sosman <Eric.Sos...@su n.comwrote:

>calimer...@fre email.it wrote:

>>Hi
>>I'musing the GMP Libraries Mathematics.
>>I need to calculate 123456789876543 21.123456787655 4456 ^
>>9876543212344 556676.67676767 6
>>How can i do ?
>>The two variables are type MPF.

> As Keith Thompson points out, your question isn't about C but
>about the GMP product.
>>
> He might also have pointed out that you don't have enough money
>to afford the answer (assuming you mean ^ to signify exponentiation) .
>The result will have about 1.6E20 decimal digits in the integer part
>alone, roughly 5.3E20 bits or 66E18 eight-bit bytes in ordinary
>positional notation. Sixty-six exabytes, or sixty-six thousand
>petabytes, or sixty-six million terabytes. I hope you've got plenty
>of RAM, and a machine able to address it all (note that a 64-bit
>address is too small).

>
isn't it worse than that?
>
log(a ^ b) = log(a) * b
>
log(a) /= 16
log(a) * b /= 10^20
>
so log(a ^ b) has 20 decimal places...
>
>
(where log is log base 10, ^ is exponentiation
/= is approximatly)
>
I must have done something wrong here...

You wrote "log(a ^ b) has 20 decimal places," and I
wrote "the result will have about 1.6E20 decimal digits,"
so we're in good agreement. If you've done something wrong
here, then so have I ...

--
Eric Sosman
esosman@ieee-dot-org.invalid

**calimero22@freemail.it** · Oct 1 '08, 01:55 PM

Re: GMP Library and POWER

On 1 Ott, 14:27, Eric Sosman <esos...@ieee-dot-org.invalidwrot e:

Nick Keighley wrote:

On 30 Sep, 19:09, Eric Sosman <Eric.Sos...@su n.comwrote:

calimer...@free mail.it wrote:
>Hi
>I'musing the GMP Libraries Mathematics.
>I need to calculate 123456789876543 21.123456787655 4456 ^
>98765432123445 56676.676767676
>How can i do ?
>The two variables are type MPF.
As Keith Thompson points out, your question isn't about C but
about the GMP product.

>

He might also have pointed out that you don't have enough money
to afford the answer (assuming you mean ^ to signify exponentiation) .
The result will have about 1.6E20 decimal digits in the integer part
alone, roughly 5.3E20 bits or 66E18 eight-bit bytes in ordinary
positional notation. Sixty-six exabytes, or sixty-six thousand
petabytes, or sixty-six million terabytes. I hope you've got plenty
of RAM, and a machine able to address it all (note that a 64-bit
address is too small).

>

isn't it worse than that?

>

log(a ^ b) = log(a) * b

>

log(a) /= 16
log(a) * b /= 10^20

>

so log(a ^ b) has 20 decimal places...

>

(where log is log base 10, ^ is exponentiation
/= is approximatly)

>

I must have done something wrong here...

>
You wrote "log(a ^ b) has 20 decimal places," and I
wrote "the result will have about 1.6E20 decimal digits,"
so we're in good agreement. If you've done something wrong
here, then so have I ...
>
--
Eric Sosman
esos...@ieee-dot-org.invalid- Nascondi testo citato
>
- Mostra testo citato -

Thank you to all.

GMP Library and POWER

GMP Library and POWER

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