• Trace[expr] generates a list of all expressions used in the evaluation of expr.
• Trace[expr, form] includes only those expressions which match form.
• Trace[expr, s] includes all evaluations which use transformation rules associated with the symbol s.
• In general, form in Trace[expr, form] is compared both with each complete expression that is evaluated, and with the tag associated with any transformation rule used in the evaluation.
• Trace[expr, lhs -> rhs] picks out expressions which match lhs, then replaces them with rhs in the list returned.
• All expressions in the list returned by Trace
are wrapped in HoldForm
• Trace returns a set of nested lists. Each individual list corresponds to a single evaluation chain, which contains the sequence of forms found for a particular expression. The list has sublists which give the histories of subsidiary evaluations.
• Example: Trace[2 3 + 4]
• The following options can be given:
• During the execution of Trace
, the settings for the form
argument, and for the options TraceOn
, can be modified by resetting the values of the global variables $TracePattern
• New in Version 2.