R help - Sep 2009 - logarithmic seq() ?

Hello,


in scilab /Matlab there are functions that can create linear sequences (like
R's
seq()) as well as logarithmic sequences.


Is there a logarithmic aequivalent of seq()?
Or maybe this would be an idea for newer R-releases,
maybe a type-option with "linear" and "logarithmic" as
parameters....?!


Ciao,
  Oliver

On 21-Sep-09 18:47:50, Oliver Bandel wrote:
> Hello,
> in scilab /Matlab there are functions that can create linear
> sequences (like R's seq()) as well as logarithmic sequences.
> 
> 
> Is there a logarithmic aequivalent of seq()?
> Or maybe this would be an idea for newer R-releases,
> maybe a type-option with "linear" and "logarithmic" as
> parameters....?!
> 
> Ciao,
>   Oliver
If you mean going from a to b by "logarithmically equal" steps,
then you can quite readily implement it yourself. For example:

exp(log(10)*seq(log10(1),log10(100),by=0.25)
[1]   1.000000   1.778279   3.162278   5.623413  10.000000
[6]  17.782794  31.622777  56.234133 100.000000

One could turn this sort of thing into a function, though a
function which includes the various ways of doing it that are
encapsulated in plain seq() would be quite complicated for a
"normal" user to write, so I think there is an argument for
your proposal!

Ted.

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E-Mail: (Ted Harding) <Ted.Harding at manchester.ac.uk>
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Date: 21-Sep-09                                       Time: 20:32:22
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On Sep 21, 2009, at 2:47 PM, Oliver Bandel wrote:
> Hello,
>
>
> in scilab /Matlab there are functions that can create linear  
> sequences (like R's
> seq()) as well as logarithmic sequences.
>
>
> Is there a logarithmic aequivalent of seq()?
> Or maybe this would be an idea for newer R-releases,
> maybe a type-option with "linear" and "logarithmic" as
> parameters....?!
>
A question came up recently to which the answer something along the  
lines of:

exp( seq(log(x[1], log(x[length(x)]), length.out=6) )

Is that what you meant by a logarithmic sequence? Or would it be:

log(1:10)  # ?

David Winsemius, MD
Heritage Laboratories
West Hartford, CT