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

[Package

*affy* version 1.8.1

Index]