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Yearstretch GASolver Reference

Setting Options

Setting Options

These options are concerned with how the solver operates internally.

To set the GASolver Options:

  1. Click the Options button from the main dialog.

  1. Enter your Options and Settings choices as follows:

Load last used settings file on GASolver start

Check this option to tell GASolver it should always load the previous saved parameter file on start-up.

Calculation precision using decimal places <value>

This allows you to control the number of decimal places to which values will be calculated and stored. GASolver rounds any values it creates to the number of places you have specified. The default is 4 decimal places.

Advanced Settings

These variables control the genetic process itself. Changing them may affect the speed or success of the solving process.

Random Number Seed <value>

GASolver uses random numbers to start the solving process. Each series of random numbers starts from a seed value. Choosing the same seed value will ensure the process repeats its previous solution path. To change the solution path you may enter different seed values. To select seed values at random select the second option.

Input Seed Range Expansion Increment <value>

GASolver creates values for input cells and to focus the search for solutions it it wise to set a minimum and maximum for these ranges. The larger the possible range the larger the search space becomes and so the longer the search may take. However, if one restricts the minimum and maximum range values too much then the solution may not be found if it is outside the range searched. One method of tackling this is to start with a narrow search range and then, if solutions are not readily located, expand the range. GASolver can do this automatically and this is signalled by an option available independently for each input cell. The amount that each input range is expanded however is controlled with a value entered here in the option dialog. The value is a percentage. If the range is allowed to expand by 1% increments then a range of say 1-100 will expand by 1% at each end, i.e. it will change the allowable range to 0.9-101.


  • population size <value>

The larger this value is the longer each generation will take to be processed but the more possible solutions will be created per generation. The lower this value the faster each generation will be processed but the smaller the range of possible solutions. It should be noted that this parameter is not likely to affect the eventual solution accuracy but is likely to affect the time taken to reach it.

  • survivors per generation <value>

This value determines the number of possible solutions that make it through to the breeding process for the next generation. A value of 1 is the minimum as this will allow only 1 of all the possible solutions to be bred into the next generation. A value which equals the population size will allow all the current solutions through to the next generation breeding process. It is usual to allow about 50% of the population to breed into the next generation. It should be noted that this parameter is not likely to affect the eventual solution accuracy but is likely to affect the time taken to reach it.


  • automate the mutation rate/fix the mutation rate <value>

The mutation rate is the percentage of brand new solutions introduced into each generation iteration to avoid stagnation, e.g. a repeating cycle of identical solutions. A low value favours pure evolution by breeding whilst a high value favours random solution location. In practice a value less than 1% may stagnate.

Check the Automation option if you would like GASolver to manage the mutation rate for you or check the Fixed option and enter a value if you care to control this variable yourself.

  1. Click OK.

See Also Save Parameters, Load Parameters, Solving Options.


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