# [Maxima] Fourier elimination

Stavros Macrakis macrakis at alum.mit.edu
Thu Dec 13 17:44:10 CST 2007

```On Dec 12, 2007 1:24 AM, Robert Dodier <robert.dodier at gmail.com> wrote:
> Here's a modification of DIMNARY (called from DIMENSION-NARY) which makes Maxima
> more eager to put in parentheses:...
> I don;'t think that causes any incorrect outputs, but whether the
> number of parentheses is appropriate is a matter of taste.
> DIMNARY as defined above seems to encourage a tasteful
> amount of parentheses. Maybe someone else can try it.

Thanks Robert.  I like this much better than the previous behavior.
It looks much better on boolean expressions, but also on mixtures of
commutative and non-commutative multiplication:

a*b.c =>
OLD  a b . c                       NEW a (b . c)
a.b*c =>
OLD  a . b c                       NEW (a . b) c
a.b*c.d =>
OLD  a . b c . d                   NEW (a . b) (c . d)

(Though I think it would look even better if .-product terms sorted to
the right of non-.-product terms, as in math usually scalar terms are
shown to the left of non-scalar expressions.)

I could only find one pathological case which looks strange, but it is
truly pathological and I don't think we need to worry:

'(a."("(a))) =>
OLD a . (a)                         NEW a . ((a))

This case actually shows that it's an improvement:

'(a."("(a+b))) =>
OLD a . (a+b)                      NEW  a . ((a+b))

The double-parens clarify that the (,) operator is there, while the
old format didn't distinguish it from a.(a+b).  But as I say,
single-argument "(" is pretty pathological.

If no one finds any problems with this change, I'd support putting it
in standard Maxima.  Thanks again, Robert.

-s
```