## Tuesday, December 18, 2007

This article is about double exponential functions. For the double exponential distribution, see Laplace distribution.
A double exponential function is a constant raised to the power of an exponential function. The general formula is $f(x) = a^{b^x}$, which grows even faster than an exponential function. For example, if a = b = 10:
Factorials grow faster than exponential functions, but much slower than double-exponential functions. Compare the hyper-exponential function, which grows even faster.

f(−1) ≈ 1.26
f(0) = 10
f(1) = 10 = googolplex Applications

Ackermann function
Big O notation