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24 Bernoulli and Euler PolynomialsProperties

§24.12 Zeros

Contents
  1. §24.12(i) Bernoulli Polynomials: Real Zeros
  2. §24.12(ii) Euler Polynomials: Real Zeros
  3. §24.12(iii) Complex Zeros
  4. §24.12(iv) Multiple Zeros

§24.12(i) Bernoulli Polynomials: Real Zeros

In the interval 0\leq x\leq 1 the only zeros of B_{2n+1}\left(x\right), n=1,2,\dotsc, are 0,\tfrac{1}{2},1, and the only zeros of B_{2n}\left(x\right)-B_{2n}, n=1,2,\dotsc, are 0,1.

For the interval \tfrac{1}{2}\leq x<\infty denote the zeros of B_{n}\left(x\right) by x_{j}^{(n)}, j=1,2,\dotsc, with

24.12.1 \tfrac{1}{2}\leq x_{1}^{(n)}\leq x_{2}^{(n)}\leq\cdots.

Then the zeros in the interval -\infty<x\leq\frac{1}{2} are 1-x_{j}^{(n)}.

When n(\geq 2) is even

and as n\to\infty with m(\geq 1) fixed,

24.12.4
x^{(n)}_{2m-1}\to m-\tfrac{1}{4},
x^{(n)}_{2m}\to m+\tfrac{1}{4}.

When n is odd x^{(n)}_{1}=\frac{1}{2}, x^{(n)}_{2}=1(n\geq 3), and as n\to\infty with m(\geq 1) fixed,

24.12.5
x^{(n)}_{2m-1}\to m-\tfrac{1}{2},
x^{(n)}_{2m}\to m.

Let R(n) be the total number of real zeros of B_{n}\left(x\right). Then R(n)=n when 1\leq n\leq 5, and

§24.12(ii) Euler Polynomials: Real Zeros

For the interval \frac{1}{2}\leq x<\infty denote the zeros of E_{n}\left(x\right) by y^{(n)}_{j}, j=1,2,\dotsc, with

24.12.7 \tfrac{1}{2}\leq y^{(n)}_{1}\leq y^{(n)}_{2}\leq\cdots.

Then the zeros in the interval -\infty<x\leq\frac{1}{2} are 1-y^{(n)}_{j}.

When n(\geq 2) is even y^{(n)}_{1}=1, and as n\to\infty with m(\geq 1) fixed,

24.12.8 y^{(n)}_{m}\to m.

When n is odd y^{(n)}_{1}=\tfrac{1}{2},

and as n\to\infty with m(\geq 1) fixed,

24.12.11 y^{(n)}_{2m}\to m-\tfrac{1}{2}.

§24.12(iii) Complex Zeros

For complex zeros of Bernoulli and Euler polynomials, see Delange (1987) and Dilcher (1988). A related topic is the irreducibility of Bernoulli and Euler polynomials. For details and references, see Dilcher (1987b), Kimura (1988), or Adelberg (1992).

§24.12(iv) Multiple Zeros

B_{n}\left(x\right), n=1,2,\dotsc, has no multiple zeros. The only polynomial E_{n}\left(x\right) with multiple zeros is E_{5}\left(x\right)=(x-\frac{1}{2})(x^{2}-x-1)^{2}.