---------- Forwarded message ----------
From: Martin Schmidt <martin.schmidt@xxxxxxxxxxxxxxxxx>
Date: Mon, Jun 22, 2009 at 12:28 PM
Subject: Re: [ferret_users] ave vs. sum and ngd
To: Peter Szabo <szabpet83@xxxxxxxxx
Peter, the answer is most probably the following example:
yes? list (1.74*31/2+8.74*30+15.34*31/2)/61
VARIABLE : (1.74*31/2+8.74*30+15.34*31/2)/61
The values at the edges are counted with half weights. However, I am
not sure about the remaining difference.
Peter Szabo wrote:
i know there is a difference between @ave and @sum, @ngd. It is not
question, but still want to post it.
I list 3 timesteps:
yes? list/nohead temp[l=16:18]
16-MAR-1962 / 16: 1.74
16-APR-1962 / 17: 8.74
16-MAY-1962 / 18: 15.34
Here is the real average for it. The mean i guess.
yes? list/nohead temp[l=16:18@sum]/3
The (weighted) "average" is slightly different. Though if there is no
missing value, they should be the same.
yes? list/nohead temp[l=16:18@ave]
Why is that weightening in @ave? The 3 timesteps are equivalent for me.
should just use the sum and dividing then?
If i use @var later on (which is also a weighted variance), should i use