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On
On[
symbol
::
tag
] switches on a message, so that it can be printed.
On[
s
] switches on tracing for the symbol s.
On[
,
, ... ] switches on several messages.
On[
] switches on tracing for all symbols.
When tracing is switched on, each evaluation of a symbol, on its own, or as a function, is printed, together with the result.
Note that the tracing information is printed when a function returns. As a result, traces of recursive functions appear in the opposite order from their calls.
On[
s
] is equivalent to On[
s
::trace].
On[
] is equivalent to On[
s
::trace] for all symbols.
See the Mathematica book: Section 1.3.11, Section 2.8.21.
See also: Off, TracePrint.
Further Examples
This switches on tracing of all symbols.
In[1]:= 
On::trace: On[] --> Null.
In[2]:= 
Set::trace: a = 5 --> 5.
Out[2]= 
In[3]:= 
a::trace: a --> 5.
2 2
Power::trace: a --> 5 .
2
Power::trace: 5 --> 25.
2
Plus::trace: a - c --> 25 - c.
2
b::trace: b[a - c] --> b[25 - c].
Out[3]= 
This switches tracing off.
In[4]:= 
THIS IS DOCUMENTATION FOR AN OBSOLETE PRODUCT. SEE THE DOCUMENTATION CENTER FOR THE LATEST INFORMATION. | |
