I have the following :

sage: R.<x> = QQ[]
sage: f = prod([R.random_element() for i in 
range(12)])+1/9939999*R.random_element(degree=24)+73/1298749837*prod([R.random_element(degree=1)
 
for i in range(24)])
sage: f.factor()

(189/2) * (x^24 +
7504997480865664356484601/1685489222385795317475600*x^23 -
86559886260704094481/5934821802648354000*x^22 -
95000942980281728893748543911/1238834578453559558344566000*x^21 -
2931680067766784265971409584453/138749472786798670534591392000*x^20 +
11515525236076630926039622515143/118928119531541717601078336000*x^19 -
13892082133194100527760884036619/227044591832943279056604096000*x^18 -
1023688594047157556459888827191071/29969886121948512835471740672000*x^17
+ 23767733432257188084673265898337/237856239063083435202156672000*x^16 +
444451745980658091387501606764119/17125649212542007334555280384000*x^15
-
738829186881482750550278987758409/39959848162598017113962320896000*x^14
- 3878836873081061546191753704623/2179628081596255478943399321600*x^13 +
7160303309088369144242103323/134544943308410832033543168000*x^12 -
57894761695290073256239016830183/119879544487794051341886962688000*x^11
+ 1127815928112361886082916771409/4439983129177557457106924544000*x^10 +
1937574800475871259018213/36180952680516582951936000*x^9 -
874200716744023754020688448559/39959848162598017113962320896000*x^8 -
1546411010199459671989/1644588758205299225088000*x^7 +
783060427300243956126025547/1427137434378500611212940032000*x^6 -
90637942795516481/3418457358325451904000*x^5 +
480191813998109156527/138749472786798670534591392000*x^4 +
44405422069/87241880498930803800*x^3 -
2595617455483/2391110940848406790860*x^2 + 2/1878659811*x +
26/20665257921)


So, we have a big polynomial with big coefficients... but irreducible. so we 
look at its roots:


sage: r=f.roots(QQbar,multiplicities=False)

sage: r[0].minpoly()

...



takes a long time. For bigger examples it even gets the following error:

sage.libs.pari.gen.PariError: not enough precomputed primes, need
primelimit ~ 516569


But the minimal polynomial was given at the construction time!


Shouldn't we just compute which is the factor of the given polynomial that 
contains the root in the cases where the algebraic number is given as a root of 
a rational polynomial?

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