Description Details Author(s) References Examples

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.

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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 `brob`

s: 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.

Robin K. S. Hankin

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

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

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 (!)
``` |

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