I need to investigate how rollmean and the trend returned from stl differ.
I am trying to find out exactly what the trend part of stl is (I have just
started coding in R and do not know fortran).  I need to extract this
because it will be used in further calculations, and it needs to be verified
to make sure that I am using the right process.   I would like to use this
to remove the seasonal component  of a time series  to investigate the
advective transport of oxygen and the local production.

I tried
d <- stl(data, s.window="periodic")
d$trend
and I get NULL

thanks

Stephen

-- 
Let's not spend our time and resources thinking about things that are so
little or so large that all they really do for us is puff us up and make us
feel like gods. We are mammals, and have not exhausted the annoying little
problems of being mammals.

-K. Mullis

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