TraditionalForm bug?
- To: mathgroup at smc.vnet.net
- Subject: [mg66068] TraditionalForm bug?
- From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
- Date: Fri, 28 Apr 2006 06:33:14 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
I just noticed something in my version of Mathematica:
$Version
5.1 for Mac OS X (October 25, 2004)
which certainly looks like a bug that should have been spotted a long
time ago. The "bug" is simply this. Evaluate
In[14]:=
Sin'
Out[14]=
cos(#1)&
This is fine. But now simple convert the above input to
TraditionalForm and evaluate it again:
In[15]:=
\!\(\*FormBox[
SuperscriptBox["sin", "â?²",
MultilineFunction->None], TraditionalForm]\)
Out[15]=
\!\(\*FormBox[
SuperscriptBox["sin", "â?²",
MultilineFunction->None], TraditionalForm]\)
What happens is that Mathematica converts Sin` to sin` and then
forgets what sin means. This does not happen if you do the same with
an argument:
In[17]:=
Sin'[x]
Out[17]=
cos(x)
In[18]:=
\!\(\*FormBox[
RowBox[{
SuperscriptBox["sin", "â?²",
MultilineFunction->None], "(", "x", ")"}], TraditionalForm]\)
Out[18]=
cos(x)
The embarrassing thing is that I discovered this while trying to show
my students the advantages of functional notation, and in particular
the fact that one can refer to functions and their derivatives
without introducing unnecessary variables. Of course this is true,
but if you sue TraditionalForm form input! This reminds me that there
was recently a discussion of whether TraditionalForm is or is not
suitable for this purpose. I recall that Paul Abbott and Daniel
Lichtblau expressed opposing views and I was tempted to enter the
fray but decided to stay out, because while my heart sided with Paul
my brain did not. As is often the case the brain seems to have been
right.
Andrzej Kozlowski