How do you write an infinite precision number class?

[Protoman]

Hi!!! Protoman here, I need to write an infinite precision number class
b/c I want to compute pi. Give me some sample code. Also, when I run my
program and it computes pi, will my computer freeze b/c it's infinite
precision? Thanks for the help!

[Markus Moll]

Hi

Protoman wrote:

Hi!!! Protoman here, I need to write an infinite precision number class
b/c I want to compute pi. Give me some sample code.
Give me all your money.
Also, when I run my
program and it computes pi, will my computer freeze b/c it's infinite
precision? Thanks for the help!

Seriously...
1) you certainly want arbitrary precision, not infinite precision
2) you should definitely do your homework on your own
3) if you get stuck, feel free to ask a more specific question

Good luck
Markus

[Kai-Uwe Bux]

Protoman wrote:

Hi!!! Protoman here,
Hi, pleased to meet you.

I need to write an infinite precision number class
b/c I want to compute pi.
Non sequitur. If you want to compute pi, all you need is to use an arbitrary
precision library. There are some available, and Google is your friend.

Give me some sample code.
Request denied: be more polite.

Also, when I run my program and it computes pi, will my computer freeze
b/c it's infinite precision?
Yes, an infinite precission calculation will freeze your computer and the
whole universe along with it.

Seriously, if you use a high/arbitrary precision library, it will allow you
to specify the precision you want. Then the program will run and either
print out a highly accurate approximation to pi or it will die on you.
Whether your computer freezes in the process depends on your operating
system and how it handles programs that have an ever growing hunger for
memory.

Thanks for the help!

You are very welcome.
Best

Kai-Uwe Bux

[Protoman]

OK, let me rephrase this:
I'd like to write an arbitary precision number class[I'd like to be
able to specify the precision in digits or bits] because my co. won't
buy any commercial classes[the procurement dept. are cheapskates].
We're writing a program for a NASA sys. that requires us to calc pi to
1,000,000,000+ digits. Don't worry about size; it'll be running on a
Cray. We're also going to use it to replace or supplant the built in
number types. If you can give me some sample code, that'd be great.
Thanks for the help.

[Jon Slaughter]

"Kai-Uwe Bux" <jk********@gmx .net> wrote in message
news:dg******** **@murdoch.acc. Virginia.EDU...

Protoman wrote:

Hi!!! Protoman here,
Hi, pleased to meet you.

I need to write an infinite precision number class
b/c I want to compute pi.

Non sequitur. If you want to compute pi, all you need is to use an
arbitrary
precision library. There are some available, and Google is your friend.

Give me some sample code.

Request denied: be more polite.

Also, when I run my program and it computes pi, will my computer freeze
b/c it's infinite precision?

Yes, an infinite precission calculation will freeze your computer and the
whole universe along with it.

lol
Seriously, if you use a high/arbitrary precision library, it will allow
you
to specify the precision you want. Then the program will run and either
print out a highly accurate approximation to pi or it will die on you.
Whether your computer freezes in the process depends on your operating
system and how it handles programs that have an ever growing hunger for
memory.

Thanks for the help!

You are very welcome.
Best

Kai-Uwe Bux

[Jon Slaughter]

"Protoman" <Pr**********@g mail.com> wrote in message
news:11******** **************@ f14g2000cwb.goo glegroups.com.. .

OK, let me rephrase this:
I'd like to write an arbitary precision number class[I'd like to be
able to specify the precision in digits or bits] because my co. won't
buy any commercial classes[the procurement dept. are cheapskates].
We're writing a program for a NASA sys. that requires us to calc pi to
1,000,000,000+ digits. Don't worry about size; it'll be running on a
Cray. We're also going to use it to replace or supplant the built in
number types. If you can give me some sample code, that'd be great.
Thanks for the help.

OMG, you writing code for Nasa?

[Protoman]

Yes really; I'm the asst. head of systems programming in the R&D Dept.
We're calculating thruster angles for a prototype ion drive engine.

[Kai-Uwe Bux]

Protoman wrote:

OK, let me rephrase this:
I'd like to write an arbitary precision number class[I'd like to be
able to specify the precision in digits or bits] because my co. won't
buy any commercial classes[the procurement dept. are cheapskates].
Use a free library. There are those as well. At least you can use them to do
a quick and dirty implementation of the class to be replaced later. That
way, your colleagues can move on with the rest of the program.

We're writing a program for a NASA sys. that requires us to calc pi to
1,000,000,000+ digits.
a ) Why would NASA need that? The known universe has a diameter on the order
of 10^28m. Thus, an error in an angle in the 50s digit after the decimal
point will project to a distance way less than the diameter of an electron
at the other end of the universe. No real world application has a need for
more than 50 digits of pi.

b) If NASA does not like open source, have them pay for the library.

Don't worry about size; it'll be running on a Cray.
No need for that. There is a digit extraction algorithm for pi. You can
produce 1,000,000,000 digits and more on any modern day PC.

We're also going to use it to replace or supplant the built in
number types. If you can give me some sample code, that'd be great.
Thanks for the help.

Well, if you really want to code that beast on your own, the best way to
start is probably still to read the relevant chapters in

D.E. Knuth: The art of computer programming Vol 2
(seminumerical algorithms)

Then, start with coding an arbitrary size unsigned int class. A cheap way to
go would be to do something like:

class Cardinal {
std::vector< unsigned long > digit;
public:
...
}; // class Cardinal

later you can use that and build a float class like so:

template < unsigned long Digits = 100 > {
class Real {

bool positive;
Cardinal mantissa;
signed long exponent;
public:
...
}; // Real<>

It does not make sense to discuss the "..." parts unless you settled on
certain algorithms.
Best

Kai-Uwe Bux

[Protoman]

OK, but how do I actually *code* it? The precision alogorithm, I mean.

[Protoman]

It's not a missile; it's a space probe. And how do I code the
prescision algorithm and conversion functs; I can figure out how to do
just about everything else but constructor, destructor, and copy
constructor. Thanks.