26 Jul
2008
26 Jul
'08
10:07 p.m.
On Sat, Jul 26, 2008 at 10:42 PM, Dan Asimov <dasimov@earthlink.net> wrote: [...]
Lessee:
sinh(x) := (e^x - e^-x)/2,
so one branch (the usual one) of the inverse function is
asinh(y) = ln(x + sqrt(x^2 + 1).
So asinh(1/2) = ln( 1/2 + sqrt(5/4) ) = ln(phi).
--Dan
More surprisingly (13/17)ln(phi) = 14700630551 / 39948938261, a ratio of two primes:)