Sample 1

For a quick start lesson in GASolver follow the sequence below with the Sample1.xls and Sample1.txt files accompanying the GASolver package.

This lesson will show you how to:

• define a simple problem for GASolver.

• change the allowable range of input cell values.

• change the conditions under which GASolver will stop searching for a better solution.

To start Sample 1:

1. Run GASolver by clicking the GASolver desktop icon.

2. Open Sample1.xls from the folder where you installed GASolver (the default folder is c:\program files\yearstretch GASolver\sample1.xls) OR run Start | Programs | Yearstretch GASolver | Sample1.

3. Click the button from the right hand of the Input Cells box.

   

4. Click the work sheet cell B14 and the address will appear in the floating box. This is the cell that contains the model's result, i.e. the cell whose value we wish to drive in a certain direction and the ultimate result of the embedded formula in the cell. The function we are using to test the system is a simple average of the 10 value cells above.

5. Click the button to return the value to the main GASolver dialog.

6. Set the Evolve Target Cell Value to Equal to and enter 500 into the text box. This is the value, or answer, that we are trying to evolve from our example.

7. Click the button at the right of the Input cells box.

8. Select the cells B3 through B12 from the sheet.

9. Click the button to return the values to the main GASolver dialog.

GASolver needs to an initial range for the input cell values. You can set these individually by clicking on each input cell in the list in turn or you can set up ranges all at once.

10. Click and a confirmation dialog appears.

Answer Yes.

GASolver will create a default set of input cell seed conditions.

We will change the default seed conditions to better meet our requirements.

11. Double click the input cell $B$3 in the input cell seed condition list to see its value conditioning dialog.

12. Change the minimum value from -1000 to 0.

13. Uncheck the Automatically expand this range if required option.

14. Click OK.

15. Repeat the input cell value conditioning for all the remaining input cell values.

You will see the input cell conditions are now all set to use values between 0 and 1000 of integer type only.

16. Click the button.

    We must now set the conditions under which GASolver will halt optimising. For the time being ignore the Start Point settings.

    

17. Change the options to accept an answer Target Cell Value Is Within 0.1 of our target value (i.e. 499.9 - 500.1)

18. Change the When Generations Reach limit to 500.

19. Change the Processing Time limit to 5 minutes.

20. Click the button. Solving will start.

You will see progress dialog.

You may stop the process at any time by clicking the Pause button.

You will see both the input changeable cells and the output results cell assume differing values in the spreadsheet as the process works towards the goal.

Version Variation: Early Excel versions may not halt immediately after you press the Pause button but will halt eventually, Excel 2000, 2002 (XP) and above will halt immediately.

When GASolver has located a solution it will show its results dialog

• If you wish to keep the solution values found then select Keep the solution found.

• If you would rather abandon the solution and restore the starting values then select to Restore the previous values.

• If you would rather like to continue to search for another then select Continue solving from here.

From this Example Lesson 1 you have learnt to tell GASolver how to solve a simple problem with some restrictions on the values it may use in input cells.

The settings for Example Lesson 1 are contained in the Sample1.txt file which may be loaded into GASolver by pressing the  button from the main dialog and locating the folder where you installed GASolver (the default folder is c:\program files\yearstretch gasolver).

See also Sample 2, Sample 3