[R] variable values

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Tim Smith

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Feb 12, 2009, 2:09:37 PM2/12/09

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Hi all,

I was working with some probabilities and wanted to store some small values. For example:

> x = 2e-250
> x
[1] 2e-250
> y = 2e-300
> y
[1] 2e-300
> z = 2e-350
> z
[1] 0

Is there any way to store a small value (e.g. 2e-350) in R?

thanks!

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David Winsemius

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Feb 13, 2009, 9:27:29 AM2/13/09

to Tim Smith, r

Step 1: Read the R-FAQ 7.31:

Step 2: Ask yourself whether it is likely that such a small value can
be sensibly distinguished from zero using a program that stores values
in double precision.

Step 3: Consider alternate methods, perhaps logarithms or programs
that are equipped to deal with arbitrary precision. There have been
threads on such strategies. I got on-topic results with an r-search
on : "very small" log probabilit*