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15 votes
4 answers
2k views

Computing minimal polynomials using LLL

I would like to use the Lenstra–Lenstra–Lovász lattice basis reduction algorithm (LLL algorithm) to compute the minimal polynomial of a (real) algebraic number $\alpha$ from a decimal approximation $a$...
Mark Bell's user avatar
  • 3,165
8 votes
1 answer
335 views

Existence of Randomized polynomial time algorithm and some arithmetic analog of $ACC^0$ circuits for Factoring of primitive polynomials before LLL?

Before LLL came along in $1982$ there was no deterministic polynomial (in degree and number of bits in coefficients) way to factor square free primitive polynomials in $\Bbb Z[x]$. However was there ...
user avatar
3 votes
0 answers
135 views

Recover cyclotomic integer with bounded coefficients from its known associate

Recall that two cyclotomic integers are called associated if their ratio is a unit in the corresponding ring of cyclotomic integers. We will view cyclotomic integers as polynomials (of degree $<\...
Max Alekseyev's user avatar
1 vote
1 answer
1k views

Computation for composition of polynomials

Let $R$ be a ring, $f(X)$ be a polynomial with coefficients in $R$ of degree $n$. It's known that for any $\alpha \in R$, one can evaluate $f$ at $\alpha$, i.e compute $f( \alpha) $ in $O(n)$ ...
user565739's user avatar
  • 1,109
0 votes
1 answer
605 views

Method to solve modular quadratic polynomial [duplicate]

If $q$ is a prime what is the best method to compute roots of a quadratic polynomial $f(x)\equiv0\bmod q^2$ which is of form $x^2+bx+c\equiv0\bmod q^2$ where $b^2-4c\equiv0\bmod q$ and $gcd(b,q)=1$ ...
Turbo's user avatar
  • 13.9k