Solver iteration report for a failed block

This report provides a detailed summary of the inner solver iteration path for failed blocks. Each row corresponds to a single inner solver iteration. Repeated rows represent a save or restore operation that the solver selectively performs. The following figure shows an example of this type of report.

In this figure, block number 882, which contains 449 equations, has failed to converge within the required tolerance. Under the Most changed variable column, the report shows the variables at their upper and lower bounds during the solver iteration. These variables restrict the solver step and cause a cutback in the solver iteration bound percentage. In this example, the cutback in the bound percentage for iteration 4 is 0.0567%. You can use this information to identify variables at their bounds, which may cause convergence difficulty in the solver.

Additionally, the Largest residual column in the report corresponds to the equation with the largest residual error during a solver iteration. You can use this information to identify the equation that struggles the most during the solver iterations.

The Notes column indicates additional information during the solver iteration. The following symbols may appear in this column:

• B: Some variables were at their bounds.

• U: The solver took an uphill iteration (that is, the residual increased).

• S: The solver detected a singular Jacobian matrix.

• J: The solver did not calculate the Jacobian matrix during this iteration and instead reused the Jacobian matrix from the previous iteration.