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Systems Optimization (SOP)

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ETH Zürich - D-ITET - TIK - SOP - PISA
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PISA for Beginners


How to use PISA

The first step in order to get familiar with PISA is to download the beginners package and try it (see below).

In the following we give a description on how to run a combination of two existing PISA modules. First you need to download the two modules and unpack the files. This will create a directory for each module.

See below for an automated way of starting up two modules.

What steps are needed to get the modules to work together?

  1. Specify the common parameter values in the config file.
    This file specifies the size (alpha) of the initial population, the number of parents (mu) the selector chooses, the number of the children (lambda) the variator produces and the number of objectives for the optimization. The documentation of each module specifies the ranges of values the module can accept. You have to specify values that satisfy the requirements of both modules. (see a PISA config file here)
  2. Choose a name (and a directory) for the communication files.
    This directory has to be accessible for both modules. You need to specify the chosen 'filenamebase' when starting each module. E.g. 'pisadir/PISA_' in Unix or 'pisadir\PISA_' in Windows. Name the config file (see point one) accordingly. In this case name it: 'PISA_cfg' and put it in the 'pisadir' directory.
  3. Specify the parameters for each module.
    Most module have their own parameters you need to specify. Each module comes with a PISA parameter file you can change and the documentation should explain their meanings. In this file you need to specify things like: seeds for random number generators, maximum number of generations, etc.
  4. First start the variator, then start the selector
    This order guarantees that no old files from the last run confuses the selector module. Start both modules on the command line giving 3 arguments for each: the parameter file with the module specific parameters, the 'filenamebase' and the polling interval. This number specifies how many seconds the module waits if it reads a state concerning the other module before reading the state variable again. In our example the command to run a module could look like: variator var_param.txt pisadir/PISA_ 0.5
  5. Look at the results.
    The documentation for the variator should describe what kind of output is generated.


The Automated Way

Most modules come with a batch file (Windows) and a shell script (Solaris and Linux) which can be used to start the modules. Additionally a PISA_configuration file (PISA_cfg) and a PISA_parameter file (modulename_param.txt) are included. In order to use this mechanism you have to do the following:

  1. Create a directory for your PISA modules, e.g. pisadir.
  2. Put the downloaded zip or tar files in this directory.
  3. Unpack both zip or tar files. A new subdirectory for each module is created.
  4. Take the PISA_cfg file from one of the two directories and put it in the pisadir directory if the default is not apropriate. (All variator packages put a PISA_cfg file directly in the pisadir directory. It will be overwritten when unpacking a new variator package in pisadir.)
  5. Check that the parameter values in PISA_cfg are ok for both modules. The respective information can be found in the 'modulename_documentation.txt' file.
  6. In Windows double click the run_modulename.bat file for the variator (and in Solaris or Linux type ./ in a shell).
  7. In Windows double click the run_modulename.bat file for the selector (and in Solaris or Linux type ./ in a shell).


Beginners Package

You can get the two demonstration programs LOTZ and SEMO as binaries (Solaris (tar),Windows (zip),Linux (tar)) together with all necessary parameter files. A step-by-step explanation of what to do and what LOTZ and SEMO are doing can be found in the README files (Solaris (html), Windows (html), Linux (html)).

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