Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.soft-sys.math.mathematica > #1783 > unrolled thread

Simplify results

Back to article view | Back to comp.soft-sys.math.mathematica

Contents

  Simplify results "Berthold Hamburger" <b-hamburger@artinso.com> - 2011-04-19 10:56 +0000
    Re: Simplify results "Sjoerd C. de Vries" <sjoerd.c.devries@gmail.com> - 2011-04-20 08:28 +0000
    Re: Simplify results Gary Wardall <gwardall@gmail.com> - 2011-04-20 08:29 +0000

#1783 — Simplify results

Hi,

This might be a silly question, so please bear with me, but I have been
scratching my head about it for some time now.

Is there a particular reason why Mathematica (8.01) simplifies the following
fraction reversing the signs in the result:

IN:

Simplify[(8a^2b^3(c^2+1)^4-6a^3b^2(c^2+1)^3+14a^4b
(c^2+1)^2)/(4a^3b^2(c^2+1)^2-10a^4b^3(c^2+1)^3)]

OUT:

(-7 a^2+3 a b (1+c^2)-4 b^2 (1+c^2)^2)/(a b (-2+5 a b (1+c^2)))

Reducing the fraction by hand gives me:

(7 a^2-3 a b (1+c^2)+4 b^2 (1+c^2)^2)/(a b (2-5 a b (1+c^2)))

Thanks

Berthold

-- 

Berthold Hamburger - Cellist/Spain

Email: behambu@artinso.com

http://www.artinso.com

http://www.astronomy.artinso.com

[toc] | [next] | [standalone]

#1791

They are the same. Both the nominator and denominator are sign-
reversed.


Cheers -- Sjoerd

More Mathematica questions answered at StackOverflow
http://stackoverflow.com/questions/tagged/mathematica


On Apr 19, 12:56 pm, "Berthold Hamburger" <b-hambur...@artinso.com>
wrote:
> Hi,
>
> This might be a silly question, so please bear with me, but I have been
> scratching my head about it for some time now.
>
> Is there a particular reason why Mathematica (8.01) simplifies the following
> fraction reversing the signs in the result:
>
> IN:
>
> Simplify[(8a^2b^3(c^2+1)^4-6a^3b^2(c^2+1)^3+14a^4b
> (c^2+1)^2)/(4a^3b^2(c^2+1)^2-10a^4b^3(c^2+1)^3)]
>
> OUT:
>
> (-7 a^2+3 a b (1+c^2)-4 b^2 (1+c^2)^2)/(a b (-2+5 a b (1+c^2)))
>
> Reducing the fraction by hand gives me:
>
> (7 a^2-3 a b (1+c^2)+4 b^2 (1+c^2)^2)/(a b (2-5 a b (1+c^2)))
>
> Thanks
>
> Berthold
>
> --
>
> Berthold Hamburger - Cellist/Spain
>
> Email: beha...@artinso.com
>
> http://www.artinso.com
>
> http://www.astronomy.artinso.com

[toc] | [prev] | [next] | [standalone]

#1799

On Apr 19, 5:56 am, "Berthold Hamburger" <b-hambur...@artinso.com>
wrote:
> Hi,
>
> This might be a silly question, so please bear with me, but I have been
> scratching my head about it for some time now.
>
> Is there a particular reason why Mathematica (8.01) simplifies the following
> fraction reversing the signs in the result:
>
> IN:
>
> Simplify[(8a^2b^3(c^2+1)^4-6a^3b^2(c^2+1)^3+14a^4b
> (c^2+1)^2)/(4a^3b^2(c^2+1)^2-10a^4b^3(c^2+1)^3)]
>
> OUT:
>
> (-7 a^2+3 a b (1+c^2)-4 b^2 (1+c^2)^2)/(a b (-2+5 a b (1+c^2)))
>
> Reducing the fraction by hand gives me:
>
> (7 a^2-3 a b (1+c^2)+4 b^2 (1+c^2)^2)/(a b (2-5 a b (1+c^2)))
>
> Thanks
>
> Berthold
>
> --
>
> Berthold Hamburger - Cellist/Spain
>
> Email: beha...@artinso.com
>
> http://www.artinso.com
>
> http://www.astronomy.artinso.com

Berthold:

I got:

(-7 a^2 + 3 a b - 4 b^2 + 3 a b c^2 - 8 b^2 c^2 -
 4 b^2 c^4)/(-2 a b + 5 a^2 b^2 + 5 a^2 b^2 c^2)

by hand which is correct too, I think.

The point being there are many equivalent forms for mathematical
expressions. Mathematica would have to be clairvoyant to know which
form you would expect to expressions to simplify into.

Good Luck

Gary Wardall

[toc] | [prev] | [standalone]

Back to top | Article view | comp.soft-sys.math.mathematica

csiph-web