On Sun, Nov 2, 2008 at 10:57 AM, Robert Dodier <[EMAIL PROTECTED]> wrote:
> William Stein wrote:
>
>> I personally Python well suited to mathematical computation,

Wow, I omitted a lot of words from that sentence.

> No problem with any computation involving literal objects.
> It's the symbolic stuff that's lacking.
>
>> and at least the approach in Python regarding undefined variables
>> is consistent with every other general purpose programming
>> language I've ever used.
>
> Well, this is an opportunity for Sage to do something usefully
> different, then.

Sage has done something different, which is to be consistent
with many mainstream general purpose programming language
(by which I mean languages such as Java, Python, C#, etc.)

>
>> But it is definitely different than Mathematica.
>
> Apparently Maple also does not require variables to be declared
> (to judge by their quick start guide). Neither does Maxima/Macsyma
> nor MuPAD nor PARI/GP ftr.

That's right -- many of the special purposes math languages don't
require variables to be defined.  A notable exception is the Magma
which requires variables to be define before using them.

>> What is wrong?  That statement Justin made or that he made it at all?
>
> It's a classic strawman. There's no evidence whatsoever in the
> original message that the o.p. (Seberino) has assumed that he knows
> "all there is to know about how to use a Computer Algebra System".

Well just for the record I know the o.p. personally, I he is an
extremely well intentioned and considerate person, and
I hope he doesn't take any offense to Justin's
also (I hope) well meaning remarks.

>> The first line of section 2 of the tutorial (about calculus) is
>> "The solve function solves equations. To use it, first specify some 
>> variables;
>> ..." and gives an example of using var.
>>
>> I guess this suggests that one needs to use var.   This would
>> be a good place in the tutorial to insert a sentence that if you
>> don't use var then you will get a NameError, and that this
>> behavior is different than in Mathematica, and there is no
>> mode to change this, since it's a basic feature of how the Python
>> language works.
>
> Well, that would be an improvement. The need to declare variables
> is different from various other packages, not just Mathematica. Some
> explanation should go in the documentation for var itself as well.
>
> FWIW

OK, let's do that.

William

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