Re: [R] integrate function

[Jari Oksanen]

On Wed, 2004-08-25 at 23:44, Peter Dalgaard wrote:
 Ronaldo Reis Jr. [EMAIL PROTECTED] writes:
 
  Is possible to integrate this diferential equation:
  
  dN/dt = Nr(1-(N/K))
  
  in R using the integrate() function?
 
 No.
  
However,  you could use 

N = K/(1 + exp(log((K-N0)/K) -r*t)),

where N0 is the population size at t=0 (that you must fix or estimate).

Causton has a long discussion about integrating this funcition on in his
Mathematics for Biologists (or something like that). Apart from that
MuPad may be free for Linux, and you can buy many other alternatives for
symbolic mathematics (Maple is available for Linux, at least). It may be
that you still have to work to get the solution you need, even with
snappy tools like that.

cheers, jari oksanen
-- 
Jari Oksanen [EMAIL PROTECTED]

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RE: [R] integrate function

[Wayne Jones]

I suggest that you check out the R package odesolve for solving this. 

However, from a more ecological standpoint (which I am guessing from the
fact that it is logistical growth) you might be interested in SOLVER.

You can find it at http://www.stams.strath.ac.uk/ecodyn/

Or indeed you might be interested in
http://www.stats.gla.ac.uk/~simon/simon/ddefit.html


Regards

Wayne Jones




-Original Message-
From: Ronaldo Reis Jr. [mailto:[EMAIL PROTECTED] 
Sent: 25 August 2004 21:02
To: R-Help
Subject: [R] integrate function

Is possible to integrate this diferential equation:

dN/dt = Nr(1-(N/K))

in R using the integrate() function?

Or any other diferential equation?

If yes, how?

If no, anybody know any software on linux that make this?

Inte
Ronaldo
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Re: [R] integrate function

[Peter Dalgaard]

Ronaldo Reis Jr. [EMAIL PROTECTED] writes:

 Is possible to integrate this diferential equation:
 
 dN/dt = Nr(1-(N/K))
 
 in R using the integrate() function?

No.
 
 Or any other diferential equation?

Only if the right hand side does not depend on the dependent variable
(N in this case) -- just plain integrals.

 If yes, how?
 
 If no, anybody know any software on linux that make this?

The odesolve package in R. 

Possibly, there's also stuff in Octave but I haven't looked lately. 

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  c/ /'_ --- Dept. of Biostatistics 2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark  Ph: (+45) 35327918
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