hlog {affy} | R Documentation

## 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 continuos odd ( f(-x)=-f(x) ) function with continous 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`.

### Author(s)

Rafael A. Irizarry

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