THE B AND T FUNCTIONS
273
has shown how the series 1) may be made to converge more
rapidly. We have for any x in 21
log (\ + x~) = x — 2 ( — 1)"
n
This on adding and subtracting from 1) gives
log <?(1 + *) = - log (1 + x) + (1 - 0)x+ I(- - 1)|
Changing here x into — x gives
log 0(1 -x)=- log (1 - x) - (1 - 0> + t(H n - 1)*
Subtracting this from the foregoing gives
.x n
n
log 0(1 + x') — log 0(1 — x')
1 + X
"I I ™ /y.2m+l
= - l0 « tzt x + 2(1 - 0)x -?2»TPT (H ^ - X)
From 225, 4
7XX
log 0(1 + x') + log 0(1 —x)= log —
Sin 7TX
This with the preceding relation gives
log 0(1 + 2:)
1 + 2: . i 7T2:
v.2m+l
(2
= (1 - <7>-i!ogi±S + log1, -l) 2 - m + x
valid in 21.
This series converges rapidly for 0<2;<|, and enables us to
compute Gr(u) in the interval 1<m<|-. The other values of 0
may be readily obtained as already observed.
228. 1. We show now with Pringsheim* that Gr(u) = T(u). for
u > 0.
We have for 0 < u < 1,
V(u n)= e~ x x u+n ~ 1 dx
=/"+/*
* Math. Annalen, vol. 31, p. 455.