BUILT-IN WOLFRAM LANGUAGE SYMBOL
specifies the number of previous lines of input and output to keep in a Wolfram System session.
- The default setting for $HistoryLength is Infinity.
- Values of In[n] and Out[n] corresponding to lines before those kept are explicitly cleared.
- Using smaller values of $HistoryLength can save substantial amounts of memory in a Wolfram System session.
The default is to save the entire history:
Change the setting to save no history:
This means the previous input can no longer be used directly:
By assigning to a variable you can still refer to previous results: