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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[{var1=val1, ...}, expr] is effectively used.
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