'Detrending' is often used before the signal power calculation.

## Usage

`detrend(x, trend = c("constant", "linear"), break_points = NULL)`

## Arguments

- x
numerical or complex, a vector or a matrix

- trend
the trend of the signal; choices are `'constant'`

and
`'linear'`

- break_points
integer vector, or `NULL`

; only used when
`trend`

is `'linear'`

to remove piecewise linear trend; will
throw warnings if `trend`

is `'constant'`

## Value

The signals with trend removed in matrix form; the number of columns
is the number of signals, and number of rows is length of the signals

## Examples

```
x <- rnorm(100, mean = 1) + c(
seq(0, 5, length.out = 50),
seq(5, 3, length.out = 50))
plot(x)
plot(detrend(x, 'constant'))
plot(detrend(x, 'linear'))
plot(detrend(x, 'linear', 50))
```