Basic Examples (2) 

Trace each step in an evaluation:

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Trace only the computations with head Times:

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Scope (10) 

Trace an empty evaluation chain:

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Trace a single step evaluation:

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Trace each branch in an evaluation:

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Trace evaluations given by definitions:

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Trace each step in an evaluation:

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Trace the operation of FoldList:

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Trace the steps in a non-standard evaluation:

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Trace each step in an evaluation:

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Include only those expressions that match _Plus:

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Trace the computations with head Plus:

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Apply a transformation rule to expressions that match a pattern:

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Modify the setting for the form argument during the execution of TraceGraph[expr,form] by resetting the value of the global variable $TracePattern:

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Options (23) 

MatchLocalNames (2) 

By default, symbols such as x match symbols with local names of the form x$nnn:

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With MatchLocalNames→False, only an explicit match of x will show up:

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TraceAbove (4) 

A recursive definition for finding Fibonacci numbers:

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Show only what sums of fib are encountered:

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Show the beginning of the evaluation chain that leads to each sum of fib:

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Show the entire evaluation chain that leads to each sum of fib:

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TraceBackward (4) 

A recursive definition for finding Fibonacci numbers:

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Show only what additions of positive integers are required:

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Show the beginning of the evaluation chain that leads to each addition:

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Show all intermediate evaluations that led to each addition:

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TraceDepth (3) 

A recursive definition for finding Fibonacci numbers:

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Trace only evaluations through depth 3:

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Trace all evaluations:

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TraceForward (4) 

A recursive definition for finding Fibonacci numbers:

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Show only what evaluations of fib are encountered:

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Show only the evaluations of fib and the results:

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Show all intermediate evaluations between calls of fib and the result:

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TraceOff (2) 

Trace evaluation of an expression that evaluates a function g:

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Omit evaluations required to get the values of g:

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TraceOn (2) 

Trace evaluation of an expression that evaluates a function g:

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Trace only evaluation inside of g:

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TraceOriginal (2) 

Trace evaluation of an expression showing evaluation chains for expressions that change:

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Show evaluation chains even for expressions that do not change:

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Applications (5) 

Trace the evaluation of control structures such as CompoundExpression:

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Trace the evaluation of conditionals such as If:

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Trace the evaluation of logical operations such as And:

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Trace the evaluation of iteration functions such as Do:

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Trace the evaluation of assignments such as SetDelayed:

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Properties and Relations (8) 

TraceGraph[expr] traces each step in the evaluation of expr:

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TraceGraph[expr,form] includes only those expressions that match form:

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This corresponds to deleting all expressions that do not match form, then deleting empty evaluation chains:

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TraceGraph gives a graph with vertices of the form Trees`TraceNode[HoldForm[expr],pos]:

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TraceGraph uses highlighted dashed edges for a sequence of evaluations:

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In contrast, TraceTree shows successive evaluations as siblings:

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TraceGraph uses solid and dashed edges for increasing and decreasing evaluation levels, respectively:

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The levels given by TraceTree correspond to the evaluation levels of subexpressions:

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Each step in the evaluation of an expression at level n is represented as Trees`TraceNode[expr,{i₁,…,i_n}]:

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The result of evaluation at level n is represented as Trees`TraceNode[expr,{i₁,…,i_n-1}]:

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Trees`TraceNode[Null,{…,1}] represents the first node in an evaluation chain when the first expression is not included:

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Trees`TraceNode[Null,{…,-1}] represents the last node in evaluation chain when the last expression is not included:

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