TraceOff
 Usage
• TraceOff 是Trace和相关函数的一个选项，指定应当关掉的追踪的形式。
Notes
• TraceOff的设置给出一个和被计算的表达式比较的模式。如果模式匹配表达式，则在计算期间关掉跟踪。模式也对和计算相关的标记进行计算。 • 可以用TraceOff避免跟踪计算的内部部分。 • 缺省设置TraceOff -> None从来不关跟踪。 • TraceOn不在TraceOff中使用。 • 在Trace的执行期间，TraceOn和TraceOff的设置可以通过重新设置全局变量$TraceOn和$TraceOff修改。
 Further Examples
Here is a recursive definition of a factorial function.
In[1]:=
|
Here is a rule for a log function.
In[2]:=
|
This shows all steps in the evaluation.
In[3]:=
|
Out[3]=
|
This shows only those steps that occur during the evaluation of fac.
In[4]:=
|
Out[4]=
|
This shows only those steps that do not occur during the evaluation of fac.
In[5]:=
|
Out[5]=
|
| 
