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MathGroup Archive 2000

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Re: Big trouble with Mathematica Code parsing -- Rant.

  • To: mathgroup at smc.vnet.net
  • Subject: [mg26261] Re: Big trouble with Mathematica Code parsing -- Rant.
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Sun, 10 Dec 2000 00:19:35 -0500 (EST)
  • Organization: Universitaet Leipzig
  • References: <90kr7d$r49@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,


can you send an example notebook/package/code ?

May be that you have forgotten some ";" 
between your commands.
like

f[x_] := Module[{y}, If[x > 0, y = 4] x]

will produce

In[]:=f[-2]

Out[]=-2 Null

But the correct definition is 

f[x_] := Module[{y}, If[x > 0, y = 4]; x]

Regards
  Jens

"Louis M. Pecora" wrote:
> 
> [[ This message was both posted and mailed: see
>    the "To," "Cc," and "Newsgroups" headers for details. ]]
> 
> {\RANT ON}
> 
> I have just spent another 3 hours debugging Mathematica code that, for
> some reason unclear to me, insists on putting Null's into the return
> values, as in
> 
>     2
> Null  Return[{1.0,2.9}]   (in which the numbers are right, but the
> Null's don't belong)
> 
> Rather than just returning
> 
> {1.0,2.9}
> 
> Where are they coming from?  Beats me.  This is the third time in the
> last month or so that I've spent the better part of a day (a few days
> in some cases) trying hard to figure why Mathematica parses my code in
> a brain-dead way.
> 
> Beware.  Adding white space and blank lines for readability can cause
> Null's  to appear and other problems.  I suspect this is partly related
> to the fact that space can be taken as a multiplication, but
> eliminating spaces and blank lines may not cure the problem.  I know.
> I've tried.
> 
> I've done things such as copy the code into a text editor then right
> back to Mathematica and then it works...until I change something or
> open up the file later and try to use it.  Then I may get a syntax
> error or just more Nulls, again.  Sometimes recopying the code out and
> in will fix it, again. Sometimes not.  But what a Kludge!
> 
> Mathematica is doing things behind the scenes to the text in its
> parsing and it messes stuff up.  Mathematica Support have responded
> with hints such as Set Save in Box Form to False, eliminate white space
> (there goes readability), make sure all lines end in ";" (that one, at
> least, makes sense).  I've done it all and still have problems.
> 
> It is ridiculous when one of the most powerful sofeware packages in the
> world cannot parse code correctly.  It cannot handle simple, clear
> white space correctly.  And it insists on changing things which cause
> failures.
> 
> These are not feature or even bugs.  They are FLAWS.
> 
> Maybe it's the automatic indenting.  I don't know.  I am totally
> frustrated.  If anyone knows of anyway to turn off or on some setting
> to get this program to just handle my code sensibly, PLEASE let me
> know.
> 
> I hope Wolfram is listening.  There is a serious upgrade-FIX needed for
> Mathematica 4.0.  Right now I would not recommend this program to
> anyone in my lab.
> 
> {\RANT OFF}
> 
> My views are my own.


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