[starlogo-users] newbie - Data import-output and discrete random number gene

[Francisco J. Zagmutt]

Thanks a lot for your prompt reply Gordon!   So I guess that I still need to 
find out about data importing and custom functions.  As you said, 
incorporating a pseudo-random number generator in the code is one option.  
In the other hand it might be a little to "expensive" since I would have to 
use a loop and this usually uses a lot of resources and interpreter time.  
Also, several discrete functions relay on factorial calculations and I think 
that factorial is not available in StarLogo (I could not find it in the math 
commands list). That is why I was thinking on maybe using custom functions 
from a lower level language (although I would rather avoid doing that!).  I 
read today that NetLogo can implement Java "extensions".

Thanks again!

Francisco

>From: Gordon McDonough <gordo at hubwest.com>
>To: "Francisco J. Zagmutt" <gerifalte28 at hotmail.com>
>Subject: Re: [starlogo-users] newbie - Data import-output and discrete 
>random number generation
>Date: Tue, 10 May 2005 21:24:26 -0600
>
>Francisco J. Zagmutt wrote:
>
>[snips]
>>- Can external data be imported in the models?  For example, can I import 
>>actual x,y coordinates to be used as turtles and patches?
>
>Great question! for minds better than mine. :)
>>
>>- Is distance calculated considering a flat surface? i.e. no adjustment 
>>for sphericity of the globe
>
>The canvas is flat, and the 'nowrap' instruction will let you measure 
>across it without finding the shortcuts across the edges.
>>
>>- Does StarLogo support random number generation other than Gaussian and 
>>uniform?  For example; is it possible to randomly generate numbers from 
>>binomial or Poisson distributions?
>
>It is pretty easy to put math into your code, so if you have a pseudorandom 
>generator you prefer, it can be put in.
>>
>>- Can detailed simulation output (other than graphs and pictures) be saved 
>>on the fly? Can numerical output be saved in flat files or any other 
>>format for posterior analyses?
>
>YES!  Using 'print' will place data in the output window and follow it with 
>a carriage return, making it easily exportable to a spreadsheet or another 
>program.
>>
>>-  In case that some of these capabilities are not available; is there a 
>>way to implement custom functions in other language (i.e. JAVA, C, 
>>FORTRAN) and call them from StarLogo?  For example, to calculate an exact 
>>binomial probability one would need a factorial function which apparently 
>>does not  currently exist in StarLogo.
>
>Yikes!
>>
>>- Is there a general "rule of thumb" for the maximum number of turtles 
>>that StarLogo can handle well?
>
>No computer will ever run fast enough some of the time.  How much time do 
>you have?  I have started programs with many thousands of agents and let it 
>run for several days at a time to see what happens.  Usually, increasing 
>the number of agents just slows down the program, although sometimes (e.g. 
>A particularly complicated setup procedure) a huge number might be more 
>likely to stop the program, or if there are complicated places in a program 
>it can make it appear as though the program is not working.  There are bugs 
>that I write unintentionally too.  For example, having every turtle 
>unnecessarily manipulate a global variable can bog a program down.  Will 
>every hundredth do just as well? Or one every cycle (turtle who # 0)
>
>I hope this helps a little bit, if you need more help, let us know, show us 
>some code, etc.
>
>Good luck!
>--
>Gordon McDonough
>Santa Fe, NM
>
>http://users.hubwest.com/gordo
>
>Equally empty
>Equally to be loved
>Equally a coming Buddha
>