StepMonitor is an option for iterative numerical computation functions that gives an expression to evaluate whenever a step is taken by the numerical method used.
The option setting is normally given as StepMonitor :> expr.
The :> is used instead of -> to avoid expr being immediately evaluated.
Whenever expr is evaluated, all variables in the numerical computation are assigned their current values.
Block[ = , ... , expr] is effectively used.
See Section 3.9.10.
See also: EvaluationMonitor, Sow, Print.
New in Version 5.0.