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Basic Question about Mathematica

• To: mathgroup at smc.vnet.net
• Subject: [mg83369] Basic Question about Mathematica
• From: dmartin19 at gmail.com
• Date: Sun, 18 Nov 2007 04:54:18 -0500 (EST)

I only started using Mathematica yesterday, so please excuse this very
newbie question.

I was working in a notebook, using help files to try to learn
Mathematica. I noticed that Mathematica uses cells for entry, and each
of my entries in a cell are tagged by numbers, such as "In[n]" and
"Out[n]" where "n" is some number.

Being new, I keep making a lot of mistakes while experimenting, and
each time when I realize the mistake, I delete the cell and start over
again. When I do this, Mathematica does not continue to number the
"In[n]" and "Out[n]" lines sequentially based on what is actually on
the notebook, but instead remembers the numbers from the deleted cells
even after I have deleted them.

Consequently, with only 10 or so cells on my notebook, I have numbers
like "In[102]" because Mathematica is remembering all the deletions,
and all the times I asked it to recalculate.

What is worse is that it seems to remember errors and variables from
the deleted cells. If I previously made a mistake with some variable
or expression and deleted it, then tried to define it again, it gives
me the same error I got before I deleted it.

Clearing the history does not help.

Is there any way to get Mathematica to totally forget stuff that I
have deleted and only evaluate whatever is in the notebook at a given
time?

It would also be great if it could renumber the "In[n]" and "Out[n]"
statements so they bear some semblance to the actual number of cells
in my notebook.

Any help is appreciated!

• Follow-Ups:
  • Re: Basic Question about Mathematica
    • From: Murray Eisenberg <murray@math.umass.edu>