# [R] Calculate negative log of the E-Values in R

John Sorkin jsorkin at grecc.umaryland.edu
Fri Feb 26 21:48:33 CET 2016

```Actually  E is not "just a computer way of saying 0". The E represents a power of 10, thus E-1 = 0.1 e-2=0.01; E therefore is not zero. Because computers generally can not perform exact calculations (for reasons including the fact that our number system is base 10 and a computer's is generally base 2) what might otherwise be a zero is often represented by a very small number such as the one you listed. 4E-108 would be 4x10^-108, a very small number indeed that is (for most but not all purposes) the same as zero.
John

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> Professor of Medicine
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> On Feb 26, 2016, at 12:29 PM, Francesco Romano <francescobryanromano at gmail.com> wrote:
>
> Sema, E is just a computer way of saying 0. For the purpose of statistical
> analysis, if you can't compute a calculation with E values (i.e. 0),
> substitute all E values with a usable constant, say 50. I stumbled across a
> few websites lately that did this.
>
> Frank Romano Ph.D.
>
>
>
> On Fri, Feb 26, 2016 at 10:53 AM, Sema Atasever <s.atasever at gmail.com>
> wrote:
>
>> Dear Authorized Sir / Madam,
>>
>> If you don't mind, I want to ask how can i calculate negative log of the
>> E-Values in R.
>>
>> *For Example: *
>> What is the negative log of the 4e-108?
>>
>> I would appreciate if you could advise me some methods.
>>
>> Thanks in advance.
>>
>>        [[alternative HTML version deleted]]
>>
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>>
>
>
>
> --
>
>    [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

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