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Problem with Summation

Posted 9 years ago
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Why i got different results? Is there a bug with the sum? Or why i got this empty Textcell with a Square?
POSTED BY: Simon Baumgarten
4 Replies
Great!  
Glad it got figured out.

--Sherlock Holmes
POSTED BY: David Reiss
The symptoms suggest that in your expression for w[q_] there is an invisible character in it.  That would account for your mysterious power of 2 in the second term of Out[44].

One way you might find if this is the case is to execute 
FullForm[w[1]]
 though I am not sure if it would show....  but if you post the notebook intself as Bruce suggests it should be easy to see if this is the case


An unrelated suggestion: never use the letter l (ell) as a variable on its own. It is almost (and for some fonts completely) indistinguisable from the number 1 (one). 
POSTED BY: David Reiss
Thank you, for the answer.

With
FullForm[w[1]]
Out[44]:= Times[-1,Cos[Subscript[\[Phi],1][t]]\[IndentingNewLine],Subscript[l,1],TextCell[""]]
i found an invisible Textcell. I deleted it. Now it works.
I dont know where it comes from, but it drived me crazy.
POSTED BY: Simon Baumgarten
Any chance you could attach a notebook (.nb) file with the code, or copy-and-paste it into
a code area?  (See  http://community.wolfram.com/groups/-/m/t/151347  for including code.)
POSTED BY: Bruce Miller
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