Computation of the regular continued fraction for Euler's constant

40. R. P. Brent, Computation of the regular continued fraction for Euler's constant, Mathematics of Computation 31 (1977), 771-777. MR 55\#9490.

Abstract: dvi (3K), pdf (82K), ps (28K).

Paper: pdf (455K).

Review by Daniel Shanks in Mathematics of Computation 32 (1978), 311: pdf (107K).

Abstract

We describe a computation, using the MP package, of the first 20,000 partial quotients in the regular continued fraction for Euler's constant gamma = 0.577... and exp(gamma) = 1.781... A preliminary step was the calculation of gamma and exp(gamma) to 20,700D. It follows from the continued fractions that, if gamma or exp(gamma) is of the form P/Q for integers P and Q, then |Q| > 1010000.

Comments

It is not known whether gamma or exp(gamma) is rational; the lower bound on Q shows that neither is a small rational.

The computation of gamma improved on an earlier (and only partially correct) result of Beyer and Waterman [Mathematics of Computation 28 (1974), 599-604].

An interesting connection with the work of Ramanujan is described in Brent [139].

For a sequel which introduced some more efficient algorithms and extended the computation, see Brent and McMillan [49].

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