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Re: Re: Front end problems!
*To*: mathgroup at smc.vnet.net
*Subject*: [mg32144] Re: [mg32127] Re: Front end problems!
*From*: Andrzej Kozlowski <andrzej at tuins.ac.jp>
*Date*: Sat, 29 Dec 2001 03:57:34 -0500 (EST)
*Sender*: owner-wri-mathgroup at wolfram.com
I have not much to add to the above except the following brief comment.
I first encountered this type of problems with version 3.0. I think, but
I am not really sure, that they used to be worse then. At that time I
adopted the following principle whcih I have followed ever since:
whenever I copy and paste anything in Mathematica I first convert
everything (the cell from which I copy and the cell into which I paste)
into InputForm. Afterwards I convert everything to StandardForm or
TraditionalForm as needed. I have never encountered any problems with
this approach.
Andrzej Kozlowski
Toyama International University
JAPAN
http://platon.c.u-tokyo.ac.jp/andrzej/
On Friday, December 28, 2001, at 04:41 PM, Alan Mason wrote:
>
> "A.K." <koru at coe.neu.edu> wrote in message
> news:a0enal$pge$1 at smc.vnet.net...
>> Hello all,
>>
>> I have been using mathematica for years now. I intensely use versions 3
> and
>> 4. While using mathematica I've encountered a mysterious
> problem -mysterious
>> to me at least- that's been recurring independent of the version.
>> Whenever I use the notebook, after a certain time and effort of
> programming
>> with correct intermediate results, I start getting peculiar outputs
>> following some more additional programming. At this point of course I
> start
>> deleting any additional material to be able to go back to the closest
>> functioning state. Alas, I end up finding this state corrupted, and get
>> truly odd outputs.
>>
>> This problem usually occurs after pasting some part of another
>> previously
>> used program. A while back I was advised to open the notebook in
>> another
>> editor and delete or add a line or two. But this remedy doesn't work
> either.
>> Hence, I end up rewriting the code.
>>
>> My major question is that, is there any other individual suffering from
> this
>> type of phenomena or are these only my omens?
>>
>> And also are there any patches, service packs or upgrades etc. that
>> I'm
>> missing maybe? Such tools would be useful in either of the two versions
> that
>> run on NT 4.0.
>>
>> Best Regards.
>>
>> Aybek Korugan
>>
> Hello,
> Alas, the problems you report are not unique to you. Sometimes, the
> error
> is obvious -- you insert a comment into a Module, hit Shift-Enter, and
> get a
> syntax error because the Frontend has lost track of the semicolon
> preceding
> the comment (looks like a typical off-by-one error). But things are not
> always this clear. Sometimes after long complicated sessions, I've
> suspected Frontend errors (with white space and comments) may be
> corrupting
> the validity of my results, but it's hard to pin down the error because
> it's
> usually invisible on the screen. And even though I'm very careful
> about my
> Mathematica hygiene -- about clearing variables, rules, etc. -- it's
> rarely
> possible to exclude user error. For instance, just giving CircleDot,
> say,
> the Attribute Flat somewhere in the code and then forgetting to clear
> it can
> cause a pattern involving CircleDot to suddenly fail to match later.
> The
> internal state of Mathematica gets very complicated and can be virtually
> impossible to understand; when this occurs, it's time to start a new
> session.
>
> As it happens, just a few days ago I was able to catch Mathematica
> red-handed, and I give the short notebook below. Here there can be no
> question of user error. Mathematica isn't handling white space
> properly.
> There may be other errors as well in longer notebooks. For
> AutoGenerated
> packages the situation is even worse than for notebooks; all too
> often, a
> package generated from a master notebook that runs perfectly will
> contain
> syntax errors which persist even after all comments have been stripped
> (great for the documentation, needless to say). There are also bugs and
> maddening inconsistencies in the keyboard-to-screen-to-file
> correspondence
> that any finished software program should have down cold. That such
> bugs
> should persist even at this late stage could be considered disgraceful
> and
> can be tolerated only because of Mathematica's unique virtues; WRI
> really
> needs to understand what's going on here and fix these problems once
> and for
> all.
>
> In the following notebook, Out[2] is wrong because of a whitespace bug.
> Since the two rules in In[2] and In[3] look alike on the screen, this is
> pernicious. Apparently, Mathematica is attempting to record additional
> formatting information in the notebook, a laudable effort. But it
> needs to
> be done correctly, in a way that permits cutting and pasting without
> error.
> I believe that cutting and pasting, together with occasional
> mishandling of
> comments, is the source of most if not all of these Frontend errors.
> Because of the Mathematica-centric approach that WRI has had to adopt
> with
> its notebooks, the parsing and analysis are considerably more difficult
> than
> with a standard Windows text editor, but the difficulties are
> presumably not
> insuperable.
> In[1]:=
> \!\(test\ = \ \ D\_z\[SmallCircle]\((y\ D\_x)\)\)
>
> Out[1]=
> \!\(D\_z\[SmallCircle]\((y\ D\_x)\)\)
>
> In[2]:=
> \!\(\(\(\[IndentingNewLine]\)\(test\ //. \ \
> \(D\_u\)\__\[SmallCircle]\ \
> \((c_\ \ D\_v_)\)\ \[RuleDelayed] \ \ c\ sc[D\_u, \
> D\_v]\ + \ \ \(\(CircleDot[D\_u, \ c]\)
> \(D\_v\)\(\ \)\)\)\)\)
>
> Out[2]=
> \!\(D\_z\[SmallCircle]\((y\ D\_x)\)\)
>
> In[3]:=
> \!\(test\ //. \
> D\_u_\[SmallCircle]\((c_\ D\_v_)\)\ \[RuleDelayed] \
> c\ sc[D\_u, \ D\_v]\ + \ CircleDot[D\_u, \ c]\ D\_v\)
>
> Out[3]=
> \!\(y\ sc[D\_z, D\_x] + D\_z\[CircleDot]y\ D\_x\)
>
> Alan
>
> PS. Actually, the rules don't look *exactly* the same in the
> notebook --
> the first is preceded by a newline, and there's an extra space before
> the
> first D, for example. However, if I delete this newline, and all the
> extra
> spaces, the result looks identical to In[3] but it still doesn't
> work! It
> looks like some effort has been made to permit better control over the
> formatting of notebooks, but the details aren't quite right. In any
> case,
> it's normal for users to consider rules that differ only by white space
> to
> be semantically identical.
>
>
>
>
>
>
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