R: Create a basis of harmonic functions.

harm {Epi} | R Documentation

## Create a basis of harmonic functions.

### Description

Returns a matrix of harmonic functions usable for modeling periodic effects

### Usage

    harm(x, ord=1, per=1, verbose=FALSE )

### Arguments

`x` | A numeric variable.
`ord` | Integer, the order of the harmonic.
`per` | Numeric, the length of the period on the `x` scale.
`verbose` | Logical: shall I tell what I do with dates?

### Details

Columns are constructed under the assumption that the periodic function has period `per` on the `x` scale. Thus, the first columns is defined as `sin(2*pi*x/per)`, `cos(2*pi*x/per)`, `sin(4*pi*x/per)` etc.

Since `sin` and `cos` are periodic functions there is no requirement that `x` be in any particular range.

### Value

A matrix with `nrow(x)` rows and 2*`deg` columns and columnnames `sin1`, `cos1`, `sin2`, `cos2` etc.

### Author(s)

Bendix Carstensen, http://bendixcarstensen.com

### Examples

    x <- seq(-1,1,0.01)
    head( harm(x,ord=2) )
    matplot( x, harm(x,ord=2), type="l", lty=1, lwd=3 )

[Package Epi version 2.42 Index]