Re: How to interpolate vectors?

• To: mathgroup at smc.vnet.net
• Subject: [mg112942] Re: How to interpolate vectors?
• From: Szymon Roziewski <szymon.roziewski at gmail.com>
• Date: Thu, 7 Oct 2010 03:35:55 -0400 (EDT)

```hello Ingolf and MathGroup,

My data is on curvilinear grid which represents geographical coordinates for
some area. I don't know how to use rectilinear parameters to represent it.
This interpolation was about to change curvilinear data from grid 448x615 to
132x145 rectilinear grid. I did it by another tool which was quite easy but
I still don't know how to deal with it in Mathematica.

//I am still working on another of your questions, but please be patient. I
//have my job to do (what I am doing just now cannot be mentioned here) and
a
//garden to harvest.

Thank You for your work I did it in a simply way just by sweeping matrices
but it's an inefficient way for doing it.
Have a good garner.

kind regards,
Simon

2010/10/5 Ingolf Dahl <ingolf.dahl at telia.com>

> Mathematica should be able to do this straight off, as long as you might
> represent the data on a rectilinear grid, just supply vectors as function
> values for the control points. An example:
>
> a = Flatten[
>  N[Table[{x, y, {Sin[x] Sin[y], Cos[x] Cos[y]}}, {x, 0, 2*Pi,
>     Pi/6}, {y, 0, 2*Pi, Pi/6}]], 1];
>
> Interpolation[a][0.3, 0.4]
>
> gives {0.116014, 0.882871}
>
> ({Sin[x] Sin[y], Cos[x] Cos[y]} /. {x -> 0.3, y -> 0.4} gives {0.115081,
> 0.879923})
>
> You might also do
>
> b = Flatten[
>  N[Table[{{x, y}, {Sin[x] Sin[y], Cos[x] Cos[y]}}, {x, 0, 2*Pi,
>     Pi/6}, {y, 0, 2*Pi, Pi/6}]], 1]
>
> Interpolation[b][0.3, 0.4]
>
> which gives the same.
> You mention something about a curvilinear grid, but maybe you could use
> some
> rectilinear parameters to represent this?
> (Longitude and latitude?) Then one might ask if an interpolation function
> is
> adequate for wind data, but that is another question, maybe outside the
> realm of Mathematica.
>
> I am still working on another of your questions, but please be patient. I
> have my job to do (what I am doing just now cannot be mentioned here) and a
> garden to harvest.
>
> Best regards
>
> Ingolf Dahl
>
> > -----Original Message-----
> > From: Szymon Roziewski [mailto:szymon.roziewski at gmail.com]
> > Sent: den 5 oktober 2010 11:37
> > To: mathgroup at smc.vnet.net
> > Subject: [mg112907] How to interpolate vectors?
> >
> > Hello there,
> > Does anybody know how to interpolate vector data e.g. wind data?
> > For example I have wind data on grid 448 columns and 615 rows on
> curvilinear
> > grid and I need this on grid 132x145 which is uniform.
> > Does Mathematica provide such a function or maybe someone has that.
> >
> > Kind regards,
> > Szymon
>
>
>

--
Z wyrazami szacunku,
Szymon Roziewski

```

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