# [R] How can I take anti log of log base 2 values in R

BXC (Bendix Carstensen) bxc at steno.dk
Fri Dec 17 16:23:03 CET 2004

```> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Saurin Jani
> Sent: Friday, December 17, 2004 3:59 PM
> To: r-help at stat.math.ethz.ch
> Subject: [R] How can I take anti log of log base 2 values in R
>
>
> Hi,
>
> I am using R for microarray data anlaysis. When I
> normalize my data, it converts all my data in to log
> base 2 values. how can I convert back to log base
> 10..is there any function in R which  I can use or how
> can I take anti  log. or is there any function in R
> for antilog.

This is a math question, from a very early course in analysis:

Any two logarithms are proportional, so:

log10(x) = K log2(x) for any x

In particular for x=2, and since log2(2)=1:

log10(2) = K

so we have in general:

log10(x) = log10(2) * log2(x)

The antilog for the natural log is exp(x),
for the base 2 log it is 2^x and
for the base 10 log it is 10^x.

Bendix Carstensen
----------------------
Bendix Carstensen
Senior Statistician
Steno Diabetes Center
Niels Steensens Vej 2
DK-2820 Gentofte
Denmark
tel: +45 44 43 87 38
mob: +45 30 75 87 38
fax: +45 44 43 07 06
bxc at steno.dk
www.biostat.ku.dk/~bxc
----------------------

> Please let me know,..if anyone knows..
>
> Thank you so much,
> Saurin
>
> =====
> Saurin's WebWorld: http://hawkmail.monmouth.edu/~s0451884
>
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