Here is an example of a real-rooted polynomial generated by my code:

1296*x^24 - 20736*x^22 + 129600*x^20 - 393984*x^18 + 584496*x^16 - 362880*x^14 
+ 62208*x^12


This I know to be real-rooted because I tested this in Mathematica.


In general my code will generate polynomials of degree ~200-300

Then is there a way to test real-rootedness inside SAGE itseld?

And given some other number (typically as a squareroot of some other integer) 
can I test if the largest root is below that threshold? 




On Sunday, May 10, 2015 at 3:09:48 PM UTC-5, vdelecroix wrote:
>
> On 10/05/15 21:51, Dima Pasechnik wrote: 
> > On Sunday, 10 May 2015 19:11:27 UTC+1, vdelecroix wrote: 
> >> On 10/05/15 19:43, Dima Pasechnik wrote: 
> >>> A random polynomial for sure won't have the properties your polynomial 
> >>> probably has (e.g. all roots real). 
> >> 
> >> Nope, but the characteristic polynomial of a "random" matrix in SL(d,R) 
> >> would ;-) 
> >> 
> > 
> > really? I'd say a random symmetric matrix in M_d(R), yes, surely, but 
> not 
> > in SL_d(R)... 
>
> Depends on your definition of random. If you pick any non-degenerate 
> generating set and look at a random product of length > d^2 then yes. 
>
> Though, I do not know for the definition of random as "uniform on all 
> matrices in SL_d(R) with coefficients less than N". 
>
> Vincent 
>

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