## General Mechanical

#### What is Iteration, Ratio, Limit and wall in MAPDL solver output window?

• Dapil J
Subscriber

Hi eveyone as I'm new to WB, I fired a non linear anlysis in anys mechanical version 2022R2, Solver output window is showing similar to attached picture, can anybody explain the terms i.e Iteration, Ratio, Limit and wall. Thanks

• Claudio Pedrazzi
Subscriber

I am slightly puzzled because a typical solver output of mine looks different:

Anyway, “Iteration” should be the number of iterations that have occurred so far in the attempt to reach convergence (equilibrium).

And “Wall” could/should be the “Wall Clock” i.e., the elapsed clock time since the analysis started.

• Aniket
Ansys Employee

The ratio is a measure of the convergence of the solver. It compares the current residual or equilibrium to the initial residual or equilibrium. A lower ratio indicates better convergence.

”Limit” refers to the convergence criterion that is used to determine when the iterative solver has found a solution that is sufficiently accurate. The convergence criterion is typically set to a small value, such as 1.0E-8 in the examples you provided, which means that the iterative solver will continue iterating until the residual error (the difference between the computed solution and the exact solution) is less than or equal to the specified convergence criterion.

The wall time represents the actual time that the solver has taken to perform the iterations.

@Claudio, your solver output seems for a direct solver, hence is different.

-Aniket

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• Claudio Pedrazzi
Subscriber

Thanks @Aniket, now I understand.