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Re: Re: MCMC in Mathematica

  • To: mathgroup at
  • Subject: [mg96030] Re: [mg96027] Re: MCMC in Mathematica
  • From: "J. McKenzie Alexander" <jalex at>
  • Date: Mon, 2 Feb 2009 06:20:23 -0500 (EST)
  • References: <gm0q4e$rmq$> <>

On 1 Feb 2009, at 09:43, Jens-Peer Kuska wrote:

> a simulation written in Mathematica blocks one Mathematica license.

Actually, that's not quite true. A standard Mathematica license, these  
days, allows several kernels to be run simultaneously on the same  
computer ? that's how the new Parallel functions work, after all.   
What this means is that you can assign a write a simulation in  
Mathematica and execute it in a kernel specific to *that* notebook,  
leaving the default kernel (plus others) free to use on other  

To see how this works, do the following:

1. If you don't have a custom kernel defined, go to "Kernel  
Configuration Options" under the Evaluation menu. The list of kernels  
by default just includes "Local". Click on "Add" and then type a name  
for the new kernel, something like "Spare Kernel". You should probably  
also select the option to append the kernel name to the In/Out prompts  
so that you don't get confused as to which kernel you are working in  
(since definitions are not shared across kernels, by default).

2. Open up a new notebook. Select your new kernel ("Spare Kernel")  
under the "Notebook's Kernel" option under the Evaluation menu.  
Evaluate some simple stuff, like "x=10".

3. Open up another new notebook. Try evaluating "x" there. If  
everything has been done correctly, your first notebook, using "Spare  
Kernel" should know the definition of x whereas the second notebook  
should not.

4. Start a long computation in the notebook using the "Spare Kernel".  
Try something like:

	Plot[Sin[x], {x,0,10}]

   and while that's working, go and do some other stuff in the second  

Even if a computation blocks one *kernel*, since most licenses include  
support for several kernels being run on the same machine, a little  
bit of care in setting up the computation will allow always allow one  
to have a free kernel to work with in Mathematica.



Dr. J. McKenzie Alexander
Department of Philosophy, Logic and Scientific Method
London School of Economics and Political Science
Houghton Street, London, WC2A 2AE

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