Logarithm of cosh

Description

Compute log(cosh(x)) without floating overflow or underflow

Usage

logcosh(x)

Arguments

Details

The computation uses asymptotic expressions for very large or very small arguments. For intermediate arguments, log(cosh(x)) is returned.

Value

Numeric vector or matrix of same dimensions as x.

Author(s)

Gordon K Smyth

Examples

x <- c(1e-8,1e-7,1e-6,1e-5,1e-4,1,3,50,800)
logcosh(x)
log(cosh(x))