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CyclotomicIndex, CyclotomicTest --
computes the index of a given cyclotomic polynomial
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CyclotomicIndex(F: RINGELEM): INT
CyclotomicTest(F: RINGELEM): INT |
The function
CyclotomicTest takes the given polynomial
F and returns the
index
n if it is the
n-th cyclotomic polynomial; otherwise, it returns
0.
To test whether a polynomial is cyclotomic, call
CyclotomicTest, and
check that the result is non-zero.
The function
CyclotomicIndex is similar but faster. It is correct if
the given polynomial is cyclotomic, but could potentially return a non-zero
value even if the input polynomial is not cyclotomic.
/**/ use R ::= QQ[x];
/**/ CyclotomicTest(x^6 +x^3 +1);
9
/**/ CyclotomicTest(x^4 -x^2 +2);
0
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