[R] I have a problem with the log2 function

[A.J. Rossini]

Frank Mattes <f.mattes at ucl.ac.uk> writes:

> Dear R users,
>
> according the help(log), the function
> log2(x) should give the natural logarithm of x.
>
> I expect in case of x=2 to to get 0.6931, however, R gives me 1 as a result.
>
> Similar, logb(2,2) gives 1 again.
>
> I'm wondering if I have missed something ?
>

I think you are looking at the help page wrong:


Description:

     'log' computes natural logarithms, 'log10' computes common (i.e.,
     base 10) logarithms, and 'log2' computes binary (i.e., base 2)
     logarithms. The general form 'logb(x, base)' computes logarithms
     with base 'base' ('log10' and 'log2' are only special cases).

     'log1p(x)' computes log(1+x) accurately also for |x| << 1 (and
     less accurately when x is approximately -1).

     'exp' computes the exponential function.

     'expm1(x)' computes exp(x) - 1 accurately also for |x| << 1.



log() is what you want.


-- 
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Biomedical and Health Informatics   University of Washington
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