To start SyntheSim simply click on the SyntheSim button 
in the Toolbar. The starting simulation will be the same as the simulation that would have been made by clicking on the Run button.
If you want to make changes to constants and lookups, referenced data or the integration technique to be used in SyntheSim you can first click on the Setup a Simulation button 
, make the desired changes and the click on the SyntheSim button.
In Vensim Standard, Professional and DSS you can also start SyntheSim by clicking on the SyntheSim button in the Simulation Control dialog. You can use this to have SyntheSim start from a resumed dataset or make other advanced adjustments.
NOTE The first time you start SyntheSim you may be asked if you want to overwrite an existing run. If you stop SyntheSim and start it again with the same run name this question will not be repeated. Each time you make changes in SyntheSim mode the existing run is overwritten.
When you start SyntheSim, a slider 
will appear below each constant or, if the constant uses a shape, above the constant name. The Lookups will also be highlighted appearing with a light blue background:
Stopping SyntheSim
To stop SyntheSim simply click on the Stop button 
. SyntheSim will also be stopped if you open another model or close Vensim.
When SyntheSim is stopped the last simulation made will be run again and saved as a normal simulation. You can use any of the analysis tools on this run.
