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VRCx_ex27.in : Invoking Alternative Linear Solvers

VRCx_ex27.in : Invoking Alternative Linear Solvers

VRCx_ex27.in : Invoking Alternative Linear Solvers

Every software package contains a full set of examples suitable for that version and are installed with the software. If you see examples here that are not in your installation you should consider updating to a later version of the software. These examples can be used by beginners and advanced users for product evaluation, teaching purposes, and self-training.

Required Modules

Victory Process

  • Core Simulator

Victory Mesh

  • 2D Meshing
  • 3D Meshing

Victory RCx

In some exceptional circumstances, when either a very unusual or very large and complicated structure is being field solved, it is possible that the default linear solver can exhibit unstable characteristics, resulting in a mathematically divergent solution, that never reaches the user specified accuracy.

In these circumstances, VictoryRCx offers several alternative solver options. The default solver is gmres. An alternative iterative solver can be invoked, using the “solver ” statement and specifying the parameter “linearsolver=pam “. Another alternative solver that has characteristics more similar to a direct solver, can be specified using the parameter “linearsolver=pas “.

In general, the default “gmres ” solver will solve in the least amount of time. However, if the problem is particularly complicated, other solvers may solve faster, if they can use fewer iterations to find each solution. In such cases, the user may try the “pam ” solver, or the more direct “pas ” solver. Each solver having merits and disadvantages. In general, the more direct the solver, the greater the ability to solve the most complex problems, but the downside is that memory usage and solution times are often slower when used for more simple problems that the default gmres solver can solve easily.

This example demonstrates these three alternatives, using two “snake ” resistors in different layers, that are arranged at right angles to each other in the dielectrically isolated interconnect layers, above a silicon substrate. Each “snake ” conductor, has a contact at each end, to evaluate it’s resistance. The capacitance is evaluated between each resistor snake and the substrate. It will be observed, that the results for all three solver options are almost identical and well within the error specified, showing that the solver does not effect the capacitance and resistance results, just the ability to solve more complex problems if required.

Images

VRCx_ex27_01.png

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