[ubuntu-uk] Curve-fitting program or package

[Robin Menneer]

On 2/24/07, Phil Bull <philbull at gmail.com> wrote:
>
> Hi Robin,
>
> On Sat, 2007-02-24 at 17:54 +0000, Robin Menneer wrote:
> > I have a problem with fitting a curve to some data and would like help
> > please.  The data are:
> > x=375, 375, 375, 355, 315, 268,195, 110, 0
> > y=2500, 2150, 1920, 1600, 1250, 936, 624, 312, 0
> > I need a program that will draw a line of best fit (for me to print)
> > according to different parameters,, especially log and power and find
> > the best for me, and give me the equation for it.
> > I notice that there is a curve fitting program for windows and assume
> > that naturally there is also one, somewhat better, for Uuntu.  Please
> > will someone tell me how to get and use it.
>
> I use Fityk. It can be a bit tricky to get an equation out of the data,
> as all it gives you are the values it derives for the variables of the
> fitting function you use. Also, it can only print basic graphs. I have a
> blog post up about it, including some basic instructions [1].
>
> What does the data relate to? It might not be valid to try and describe
> all of the data with one function.
>
> Thanks,
>
> Phil
>
> [1] - http://philbull.livejournal.com/20243.html


I've had a brief look at your paper and the Fityk site and it looks very
useful - it's too late for me to look at it this evening.  I'm no academic,
aged 75 and did a small bit non-parametic stats 35 years ago, which I've
forgotten.  What we have is the profile of a Cornish hedge.  You can see the
curve in the sides of the Guild of Cornish Hedgers' logo at
www.cornishhedges.com.  The data listed above relate to one side of the
hedge.
Some of the graphing points we know, and we have drawn by pencil on paper a
graph by interpolation.  We have derived the data by direct measurement from
this graph.  I need to convert this amateurish effort into an equation that
I can then use to print out a curve from it, and to have the equation to
hand for people who ask what it's like, and to print out for themselves.
There is also the engineering aspect because the curve acts like an arch on
its side, locking itself as the hedge settles.  I hope this answers youir
query.
 Kind regards,
Robin

--
> Phil Bull
> http://www.launchpad.net/people/philbull
>
>
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