executive_control set solver_parameters
This command provides a means to select between the harwel, calahan, umf and auto integration solvers in Adams. This selection is made on a model by model basis.
Therefore, each time you submit the model, the chosen solver will be used until this command is used to select the alternative. For a complete description of these solvers, see the Adams documentation.
Format:
executive_control set solver_parameters |
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model_name= | model_name |
solver_type = | solver_identifer_string |
Example:
executive_control set solver_parameters & |
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model_name = | model_1 & |
solver_type = | calahan |
Description:
Parameter | Value Type | Description |
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model_name | String | Specifies the model to be modified. You use this parameter to identify the existing model to be affected with this command. |
solver_type | String | Specifies that the HARWELL, CALAHAN, UMF or AUTO integration solvers is to be used in Adams for simulation of the model specified in the MODEL_NAME parameter. Each time you submit the model to be analyzed, the chosen solver will be used until this command is used to select the alternative. |
Extended Definition:
1. Specifies the model that is to be modified. You use this parameter to identify the existing model to be affected with this command. You may identify a model by typing its name or by picking it from the screen. If the model is not visible on the screen, you must type the name. You may also find it convenient to type the name even if the model is displayed. You must separate multiple model names by commas. If the model is visible in one of your views, you may identify it by picking on any of the graphics associated with it.
2. Solver types
a. CALAHAN
Specifies that Adams Solver (FORTRAN) is to use the CALAHAN solver exclusively. The Calahan solver is usually faster than the Harwell solver, but it cannot analyze systems with redundant constraints.
b. HARWELL
Specifies that Adams Solver (FORTRAN) is to use the HARWELL solver exclusively. The Harwell solver can analyze systems with redundant constraints, but is usually slower than the Calahan solver. The CALAHAN and HARWELL solvers use somewhat different strategies for picking pivots during the linear solution.
If one solver is experiencing difficulties solving an ill-conditioned model, you may try the other solver. One may work better on a particular model than the other. Even though you deactivate all your redundant constraints, Adams Solver (FORTRAN) does not allow you to use the Calahan solver. If (under these circumstances) you issue the LSOLVER/CALAHAN command, Adams Solver (FORTRAN) returns the message: “Changing to the CALAHAN solver is not allowed for this model due to the presence of redundant constraints.” To avoid this problem, deactivate all your redundant constraints, run a short simulation, and then issue the LSOLVER/CALAHAN command.
c. UMF
Specifies that Adams Solver (C++) is to use the UMF solver exclusively. The UMF solver is typically faster for models with very large number of equations (>4000).
d. AUTO
Specifies that Adams Solver (C++) is permitted to decide which solver to use based on the number of equations in the model and the amount of Jacobian fill.