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From: Rune Allnor <allnor@tele.ntnu.no>
Newsgroups: comp.soft-sys.matlab
Subject: Re: mean direction
Date: Tue, 31 May 2011 03:26:01 -0700 (PDT)
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On May 31, 12:21 pm, "ClauDe " <acerxen...@hotmail.com> wrote:
> > The result is wrong; it should obviously be 123.4 degrees.
>
> > Seriously, what kind of response do you expect to get?
> > You don't say anythiong about how these data have been
> > measured, what the variables represent, how you have
> > got your first result, or why you expect the result
> > you indicate.
>
> > Or defined what you mean by the term 'mean direction'.
>
> > Answer the questions indicated above (not so much for us
> > as for yourself), and you might eventually be getting
> > somewhere.
>
> > Rune
>
> hey Rune,
>
> ok, lets see.
> I have data of the current directions and velocities from moored Currentmeter. The data start point is Nov2009 and end is Aug2010.
> With these data I plotted a stickplot(drawn by currentvelocity and direction), that indicates/shows an average direction towards the South-East (by eye). I also plotted these data as a PVD (progressive vector diagram) which makes "pseudo trajectories" and it shows an South-East direction as well (by eye).

Ok, four questions:

1) Where is the reference direction (phi = 0) on the compass?
2) Where is the reference direction (phi = 0) in polar coordinates?
3) How does the vector change when dphi > 0 on the compass?
4) How does the vector change when dphi > 0 in polar corodinates?

Rune