Length feature
- To: mathgroup at yoda.physics.unc.edu (Mathematica User's Group)
- Subject: Length feature
- From: Keith Clay <clay at galileo.phys.washington.edu>
- Date: Fri, 20 Aug 93 1:30:52 MDT
Okay, somebody explain it to me. I can't fathom the following feature
of the Length function:
In[1]:= s = 5
Out[1]= 5
In[2]:= t = x
Out[2]= x
In[3]:= sum = s+t
Out[3]= 5 + x (* so far, so good *)
In[4]:= Length[sum]
Out[4]= 2 (* still looks good *)
In[5]:= Length[t]
Out[5]= 0 (* zero? *)
In[6]:= Length[s]
Out[6]= 0 (* zero? *)
This makes it impossible to write code that reads
Do[ blah; blah; blah, {j, 1, Length[expr]} ]
without defining something like
MyLength[expr_]:= Max[ 1, Length[expr] ]
which works but seems rather silly.
Is there a reason why Length[t] = 0?
Thanks,
Keith
clay at galileo.phys.washington.edu