Brobdingnag-package: Very Large Numbers in R

Description Details Author(s) References Examples

Description

Handles very large numbers in R. Real numbers are held using their natural logarithms, plus a logical flag indicating sign. The package includes a vignette that gives a step-by-step introduction to using S4 methods.

Details

The DESCRIPTION file: This package was not yet installed at build time.

Index: This package was not yet installed at build time.
Real numbers are represented by two objects: a real, holding the logarithm of their absolute values; and a logical, indicating the sign. Multiplication and exponentiation are easy: the challenge is addition. This is achieved using the (trivial) identity log(e^x+e^y)=x+log(1+e^(y-x)) where, WLOG, y<x.

Complex numbers are stored as a pair of brobs: objects of class glub.

The package is a simple example of S4 methods.

However, it could be viewed as a cautionary tale: the underlying R concepts are easy yet the S4 implementation is long and difficult. I would not recommend using S4 methods for a package as simple as this; S3 methods would have been perfectly adequate. I would suggest that S4 methods should only be used when S3 methods are demonstrably inadequate.

Author(s)

Robin K. S. Hankin

Maintainer: Robin K. S. Hankin <[email protected]>

References

R. K. S. Hankin 2007. “Very Large Numbers in R: Introducing Package Brobdingnag”. R News, volume 7, number 3, pages 15-16

Examples

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
googol <- as.brob(10)^100

googol
googol + googol/2

1/(googol + 1e99)

(1:10)^googol

googolplex <- 10^googol

googolplex

googolplex * googol  # practically the same as googolplex (!)

Brobdingnag documentation built on May 2, 2019, 8:46 a.m.