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From: Rune Allnor <allnor@tele.ntnu.no>
Newsgroups: comp.soft-sys.matlab
Subject: Re: River miles
Date: Tue, 18 Nov 2008 07:27:25 -0800 (PST)
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On 18 Nov, 16:13, "Travis" <sinuso...@hotmail.com> wrote:
> Rune Allnor <all...@tele.ntnu.no> wrote in message <6875d2af-8eb2-443a-a8=
31-d4c1773c1...@c36g2000prc.googlegroups.com>...

> =A0Rune the river was mapped using a GPS that recorded time, posiion, and=
 heading each time the heading changed. =A0It was then interpolated so that=
 data taken between heading chages have unique lat/long values. =A0Are you =
suggesting that I break the river up into segments that do not double back =
on themselves

Yes. Use the segments between consecutive (lat,long) points
as basis.

> and use interp1 on each segment?

No. Interpolate the whole curve.

>=A0I have a 60 mile stretch of river to do this for. =A0

No need to do that manually. The idea is to sort
the data not according to lat or long, but according
to travelled/accumulated distance.

The distance serves as a parameter, and so the
(lat, long) path becomes an arbitrary parametric
curve in the plane. Once you see this basic idea
the rest is (almost) trivial.

Rune