affy (version 1.50.0)

hlog: Hybrid Log

Description

Given a constant c this function returns x if x is less than c and sign(x)*(c*log(abs(x)/c) + c) if its not. Notice this is a continuous odd ( f(-x)=-f(x) ) function with continuous first derivative. The main purpose is to perform log transformation when one has negative numbers, for example for PM-MM.

Usage

hlog(x, constant=1)

Arguments

x

a number.

constant

the constant c (see description).

Details

If constant is less than or equal to 0 log(x) is returned for all x. If constant is infinity x is returned for all x.