Bourbaki

Proposition 5

Tag 08JH, permanent. Cite it as [Bourbaki, Tag 08JH].

Functions of a Real Variable, chapter VII, § 2. THE GAMMA FUNCTION IN THE COMPLEX DOMAIN

Along the filter F\mathfrak{F} one has (for every integer p⩾1p \geqslant 1), the asymptotic expansion

Γ′(z)Γ(z)=log⁡z−12z−∑k=1pb2k2k1z2k+O(1(ω(z))2p+1). \frac{\Gamma'(z)}{\Gamma(z)} = \log z - \frac{1}{2z} - \sum_{k=1}^{p} \frac{b_{2k}}{2k} \frac{1}{z^{2k}} + O \left( \frac{1}{(\omega(z))^{2p+1}} \right).

Instead of prop. 2 of VII, p. 318, one uses the formula

∫xx+1Γ′(t)Γ(t) dt=log⁡Γ(x+1)−log⁡Γ(x)=log⁡x \int_{x}^{x+1} \frac{\Gamma'(t)}{\Gamma(t)} \, dt = \log \Gamma(x+1) - \log \Gamma(x) = \log x

in order to determine the constant.

Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.

Cited by

Nothing.

Cites

Transcribed from the printed volume. Not translated.