An (undocumented?) feature of CompoundExpression and Out
- To: mathgroup at smc.vnet.net
- Subject: [mg76090] An (undocumented?) feature of CompoundExpression and Out
- From: Szabolcs <szhorvat at gmail.com>
- Date: Wed, 16 May 2007 05:26:20 -0400 (EDT)
- Organization: University of Bergen
I always thought that % was set to the result of the last evaluation. But it seems that this is not always the case. In[1]:= 1 Out[1]= 1 In[2]:= % Out[2]= 1 In[3]:= 2; In[4]:= % Out[4]= 2 In[5]:= 3;Null In[6]:= % Out[6]= 3 In[7]:= 4;Print[] In[8]:= % Out[8]= 4 In[9]:= 5;; (* Mathematica 5.2 *) In[10]:= % Out[10]= 5 Note that a; and a;Null are both equivalent to CompoundExpression[a, Null]. It seems that all those arguments at the end of CompoundExpression that evaluate to Null are ignored when % is set. I never expected this behaviour, therefore I have never before tried to use % when the previous expression was terminated by a semicolon. I hope that this information will be useful for someone who thought about ; the same way as I did. :-) Szabolcs