[Date Index] [Thread Index] [Author Index]

Re: FullSimplify fails for very large numbers and powers

• To: mathgroup at smc.vnet.net
• Subject: [mg89938] Re: FullSimplify fails for very large numbers and powers
• From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
• Date: Wed, 25 Jun 2008 06:23:13 -0400 (EDT)
• Organization: The Open University, Milton Keynes, UK
• References: <g3q7hv$af3$1@smc.vnet.net>

Paul Schneider wrote:
> Dear newsgroup,
> 
> FullSimplify (Mathematica 6 and 5.2) does not simplify the expression:
> 
> (-1505046085600344525396741688335403635402237542400000000000000000000000000*(-kth 
> + 2*k*r)^187*(kth - 2*k*r + 6*s*(-2*k*rho + s))^6*
>    (kth - 2*k*r + 8*s*(-2*k*rho + s))^6*((k^196*(kth + 
> s^2))/(3010092171200689050793483376670807270804475084800000000000000000000000000*(-kth 
> + 2*k*r)^187*
>       (kth - 2*k*r + 6*s*(-2*k*rho + s))^6*(kth - 2*k*r + 8*s*(-2*k*rho 
> + s))^6) + (k^196*(4*k^2 - 4*k*rho*s + s^2))/
>  
> (3010092171200689050793483376670807270804475084800000000000000000000000000*(-kth 
> + 2*k*r)^187*(kth - 2*k*r + 6*s*(-2*k*rho + s))^6*
>       (kth - 2*k*r + 8*s*(-2*k*rho + s))^6)))/k^199
> 
> to the much nicer
> 
> -(4*k^2 + kth - 4*k*rho*s + 2*s^2)/(2*k^3)
> 
> Do you have tips on how I could achieve this?
> 
> Thank you,
> 
> Paul
> 
> PS: the expressions are in InputForm. Somehow the power signs get lost 
> when pasting from Thunderbird. Pasting from Kmail seems to work.
> 

Since you have a rational expression (I have called it expr1 in the 
example below), it is always good to try *Together[]*, as you can see:

In[2]:= expr1 // Together

Out[2]= (-4 k^2 - kth + 4 k rho s - 2 s^2)/(2 k^3)

Regards,
-- Jean-Marc