## spectral (spctrl)

key: `spctrl `

type: ff(ff)*

- float: wavelength (nm)
- float: amplitude

## Description

A point sampled spectral distribution. Reconstruction with linear interpolation
is suggested. Below the minimum specified wavelength, the amplitude associated
with the minimum specified wavelength should be used. Above the maximum
specified wavelength, the amplitude associated with the maximum specified
wavelength should be used.

A jump discontinuity in the spectrum can be represented by using two
data points with the same wavelength. In this case the value at that wavelength
is the value of the latter pair (i.e. its right continuous).

## Restrictions

Wavelengths should be described in ascending order.

## Examples

spctrl 400 0.2 700 0.6 end % a reddish color

spctrl 400 0 400 1 500 1 500 0 end % blue box funtion primary [400,500)