Bug?

On Sunday 26 October 2008 17:53:30 akim wrote:

> I noticed when I type in wxmaxima  diff((x^2+1)/x, x); (or do it
> with the grafical way calculus>differentiate) the answer is
> 2-((x^2+1)/x^2).
>
> Why doesn't it show the shortest answer 1-(1/x^2) ?
>
> But when I type expand(diff((x^2+1)/x, x)); it shows the shortest
> answer 1-(1/x^2)
>
> What is this "expand" ?

Type "? expand" to see the documentation for expand. Also check
"? rat" and the Maxima manual

  http://maxima.sourceforge.net/docs/manual/en/maxima_7.html
  http://maxima.sourceforge.net/docs/manual/en/maxima_12.html

> Can I acces to it via the grafical wxmaxima menu, that the answer of
> everything I differentiate is the shortest?

Expanding diff results may be a bad idea. For example,

  (%i1) diff ((x-6)^10, x);

  (%o1) 10*(x-6)^9
  (%i2) expand (%);

  (%o2) 10*x^9-540*x^8+12960*x^7-181440*x^6+1632960*x^5
  -9797760*x^4+39191040*x^3-100776960*x^2+151165440*x-100776960

You should call simplification/expansion only if needed.

-- 
Setting Orange, Aftermath 8 YOLD 3174
Alexey Beshenov  http://beshenov.ru/