Simulator > Running models > Set solver properties for simulation 
Accessing Solver properties
To view or edit the Solver properties go to the run controls toolbar and click on the Edit Solver icon .
Setting Solver Properties in the Excel model process sheet
Solver 
Method 
BE 


 
Options are: BE, Rosen, LSODA 

Accuracy 
1.00E02 


 
Allowable range: 1e2 to 1e8 
With the Solver keyword you can set the accuracy and method for integrating the model. The abbreviations for the solver methods are:
BE  Backwards Euler 
Rosen  Rosenbrock 
LSODA  LSODA 
Editing for number of points to be plotted
You can select a number of points using the Solver Properties dialog. You can also define the number of points on your process tab:
Solver 
Points 
120 
Changing the integration method (solver type)
Backwards Euler
In general it will take more steps than the other solvers because it is a lower order solver. The run time of Backwards Euler can increase dramatically if solver accuracy is increased, so should only be used at low accuracies (e.g. 1e2 or 1e3). Backwards Euler explicitly prevents any integrated variable becoming negative, which means it can behave better at these lower accuracies.
LSODA
The LSODA solver is a third party ODE solver. It is accurate, but can tend to run slowly for many applications. LSODA actually comprises two solvers, the nonstiff solver AdamsMoulton, and the stiff solver BDF (Backward Differentiation formula). It switches between these two depending on how stiff the problem is. The LSODA solver originates in the netlib repository.
Editing solver accuracy
The solver accuracy can also be set. The default accuracy (0.001) is normally sufficient, but this can be adjusted if higher accuracy is required. Available accuracies range from 0.01 to 1x10^{8}. Increasing the accuracy will in general increase runtime, but the effect may only be significant with very high accuracies (1x10^{6} to 1x10^{8}).
What are 'Solver steps', 'Total time' and 'Number of Equations'
’Solver steps’, ‘Total time’ and ‘Number of Equations’ are indicators of the solver run. They are updated after each run and can be used to compare solvers/models for run times:
Models that run slowly
Show me more on factors that affect run time.
Show me help on troubleshooting slow models.