       RE: Factoring question

• To: mathgroup at smc.vnet.net
• Subject: [mg35309] RE: [mg35293] Factoring question
• From: "David Park" <djmp at earthlink.net>
• Date: Mon, 8 Jul 2002 03:15:44 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

```Steven,

Why don't you post the factoring problem to MathGroup? Duplicate the input
cell, convert it to InputForm (use Ctrl-Shift-I), then copy and paste it to
a posting. Someone might be able to say something interesting about it.

In general, the more complicated Mathematica routines are written in C code
and the internal steps are not available to the user. Many of the algorithms
are quite complex and technical and often handle more general cases than you
are thinking of. So, you probably would not learn much from seeing the
steps. Some of the algorithms may also, for all we know, contain a number of
hacks. It would be a little like watching sausage being made.

One of the problems for beginners in math and Mathematica, is that
Mathematica evaluates everything it can as far as it can. Sometimes students
and teachers would like to take things step by step. Often (perhaps not in
the factoring case) it is possible to do this by writing your own routines
or using more basic Mathematica commands. For example, students would often
like to use Mathematica to solve equations step by step. (The Solve routine
hides all the steps.) At my web site I have a high school notebook that
shows how to do this. Sometimes you can do a more controlled evaluation by
putting an expression in HoldForm and then evaluating parts. There is a
package at my web site called ExpressionManipulation that contains routines
for doing more precise manipulation of expressions.

Mathematica is a very general and powerful mathematical system, but often
you will have to write specific routines to do specific problems. It is a
bit shocking but true that this is often the case even with "simple"
problems.

David Park

> From: Steven Hodgen [mailto:shodgen at mindspring.com]
To: mathgroup at smc.vnet.net
>
> Hello,
>
> I just purchased Mathematica 4.1.  I'm taking precalculus and
> wanted to try
> a tough factoring problem, since the teacher couldn't do it either.
> Mathematica get's the correct answer, but I'm interrested in seeing how it
> got there.  Is there a way to turn on some sort of trace feature where it
> shows each step it used to get the the final result?
>
> Thanks!
>
> --Steven
>

```

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