## Aligned spectra

In the simplest case, the spectra have all the same resolution, reference channel and reference value: they are aligned and the channel mode (SET ALIGN CHANNEL) can be used. The intensity (temperature) and weight of the output sum are derived from a simple weighted mean of the input spectra:
On return, weight array can vary across the abscissae axis, e.g. in COMPOSITE mode the overlapping channels typically have a double weight compared to the side channels.