id,summary,reporter,owner,description,type,status,priority,milestone,component,resolution,keywords,cc,merged,author,reviewer,upstream,work_issues,branch,commit,dependencies,stopgaps
18242,Use composed_op for QQbar exactification,pernici,,"In #18356, is implemented an algorithm for computing the composed sum, difference, product and division of two polynomials. That can be used to fasten exactification in QQbar.
See also #17886.
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From the older description
Here is an example in which a fast algorithm for resultants makes a difference in timings:
{{{
sage: from sage.calculus.calculus import minpoly
sage: ex = solve(x^4 + x^3 + sqrt(2)*x + 1 == 0, x)[0].rhs()
sage: time minpoly(ex, algorithm='algebraic')
Wall time: 6.81 s
x^8 + 2*x^7 + x^6 + 2*x^4 + 2*x^3 - 2*x^2 + 1
}}}
in commit 12a1053f78c9efee9f3e6c88eb2c1c89d2db4312
it takes 31s; the difference in timings is in the computation of resultants.",enhancement,new,major,sage-7.1,number fields,,qqbar resultant exactify minpoly,mmezzarobba gagern,,,,N/A,,u/pernici/ticket/18242,e0626dcabde6434cedd0c8736df198065b7a01d6,#17886,