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Length feature


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





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