prod_spectra: Multiply two spectra, even if the wavelengths values differ
Description
The wavelength vectors of the two spectra are merged, and the missing
spectral values are calculated by interpolation. After this, the two spectral
values at each wavelength are added.
a character string with value "union" or "intersection".
na.rm
a logical value, if TRUE, not the default, NAs in the input are
replaced with zeros.
Value
a dataframe with two numeric variables
w.length
A numeric
vector with the wavelengths (nm) obtained by "fusing" w.length1 and
w.length2. w.length contains all the unique vales, sorted in ascending
order.
s.irrad
A numeric vector with the sum of the two spectral
values at each wavelength.
Details
If trim=="union" spectral values are calculated for the whole range
of wavelengths covered by at least one of the input spectra, and missing
values are set in each input spectrum to zero before addition. If
trim=="intersection" then the range of wavelengths covered by both input
spectra is returned, and the non-overlapping regions discarded. If
w.length2==NULL, it is assumed that both spectra are measured at the same
wavelengths, and a simple addition is used, ensuring fast calculation.