# Model functions

## vect() function

vect(`t`)
is used in a multivariate analysis on a multivariate set of
covariates (`v`) to pair them with the variates.
The test example included

channel 2
signal !G 93 # 93 slides
background !G 93
dart.asd !ASUV
signal ~ Trait.channel Trait.channel.vect(back) ...

to fit a slide specific regression of signal
on background.
In this example, signal is a multivariate set of 93 variates
and back is a set of 93 covariates.
The vect() function strings out the covariate values
in the same manner that the response variables are processed.
The signal values relate to either the Red or Green channels.
So for each slide and channel, we need to fit a simple regression
of signal ~ mu back. But the data for the 93 slides
is presented in parallel. If it were presented in series, with
a factor slide indexing the slides, the equivalent model would be
signal ~ slide.channel slide.channel.back.
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