Extremely large double precision...?

Quote:

>Hey all,

>I need help extending a number to more digits of precision than the built

>in datatype(s) permit. The long double, for example, can hold a number to

>10^4932, but can only do 19 digits of precision

>So, if a long double only provides a number like such:

> 12345678912345678910000000.0 (19 digits)

>I need to be able to represent the entire number with all precision like

>such:

> 12345678912345678912345678.0 (26 digits)

>so that the precision is complete. I also need to be able to do numbers

>27+ digits

>Can anyone help me please?

You need to look into an extended or arbitrary precision arithmetic

library. The Cephes library contains one:

http://www.netlib.org/cephes/index.html

From the docs:

" This computer software library is a collection of more than

400 high quality mathematical routines for scientific and

engineering applications. All are written entirely in C

language. Many of the functions are supplied in six different

arithmetic precisions: 32 bit single (24-bit significand), 64 bit

IEEE double (53-bit), 64 bit DEC (56-bit), 80 or 96 bit IEEE long

double (64-bit), and extended precision formats having 144-bit

and 336-bit significands. The extended precision arithmetic is

included with the function library."

Also go here:

http://monet.uwaterloo.ca/blitz/oon.html#libraries

and check out the "Multiprecision data types" section, which lists a

number of free arbitrary precision packages. Let me know if you find a

good one. :)

As for commercial offerings, I think Rogue Wave sells an extended

precision package aimed at financial users.

--

Doug Harrison