Function `vanderMonde()`

generates Vandermonde matrices, the `hyperSpec`

method generates a `hyperSpec`

object containing the Vandermonde matrix
of the wavelengths of a `hyperSpec`

object.

```
vanderMonde(x, order, ...)
# S4 method for hyperSpec
vanderMonde(x, order, ..., normalize.wl = normalize01)
```

## Arguments

- x
object to evaluate the polynomial on

- order
of the polynomial

- ...
hyperSpec method: further arguments to `decomposition()`

- normalize.wl
function to transform the wavelengths before evaluating
the polynomial (or other function). `normalize01()`

maps
the wavelength range to the interval [0, 1]. Use `base::I()`

to
turn off.

## Value

Vandermonde matrix
`hyperSpec`

method: hyperSpec object containing Vandermonde matrix
as spectra and an additional column `$.vdm.order`

giving the order
of each spectrum (term).

## Details

It is often numerically preferable to map `wl(x)`

to [0, 1], see the
example.

## Examples

```
plot(vanderMonde(flu, 2))
plot(vanderMonde(flu, 2, normalize.wl = I))
```