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Re: SCAT2GRIDGAUSS_YZ



Hi Sophie,
You're absolutely right. The documentation in the Users Guide has been corrected for all the SCAT2GRID functions. Notice too that the information about the cutoff parameters has been updated; the original author of theGaussian gridding code corrected my earlier misunderstanding about the cutoff for deciding how far out to look for scattered points to be included in the sum for a given output grid location.

Ansley

Sophie Cravatte wrote:

Hi Ansley,

The documentation on the web needs indeed to be changed, because it is
written that F may be a function of time (and not of X). It is also
written that the result axes are: X: normal (no axis); Y: inherited from
XAXPTS, Z also and T inherited from F.

Thanks for your help!

SOphie





On Wed, 2005-06-01 at 23:54, Ansley Manke wrote:

Hi Sophie,
Billy gives good arguments for why you might not want to use one of
the scat2grid_yz functions at all. I just want to add that the way
you're reading your data is the reason for the result being in i, y,
and z (and it shows where we need to clarify the documentation.) Your
data are lists of values on an I axis. If you look at the function
details

yes? show function SCAT2GRIDLAPLACE_YZ
SCAT2GRIDLAPLACE_YZ(YPTS,ZPTS,F,YAXPTS,ZAXPTS,CAY,NRNG)
Use Laplace interpolation to grid scattered data to a YZ grid.
YPTS: y-coordinates of scattered input triples
ZPTS: z-coordinates of scattered input triples
F: F(Y,Z) 3rd component of scattered input triples. May be fcn of
X and/or T YAXPTS: Y axis coordinates of a regular output grid
ZAXPTS: Z axis coordinates of a regular output grid
CAY: Interpolation parameter: CAY
NRNG: Interpolation parameter: NRNG


You will see that the third argument "F(Y,Z) may be fcn of X and/or
T". This means that one could use the function to grid a whole set of
Y-Z slices, at different values of X. (or, think of a whole set of
x-y planes at different Z levels with one of the scat2grid*xy
functions).

If you do this problem with scat2gridgauss_yz, make the lat, depth,
temp values be on a Y or Z axis.

let ylat = YSEQUENCE(lat)
let ydepth = YSEQUENCE(depth)
let ysalt = YSEQUENCE(salt)
let salinite
=SCAT2GRIDGAUSS_YZ(ylat,ydepth,ysalt,y[gy=yaxs],z[gz=zaxs],2,2,2,2)
Ansley

Sophie Cravatte wrote:

Dear Ferret users,

I can't figure out how to use the function SCAT2GRIDGAUSS_YZ to grid
scattered data to a YZ grid.
Here is my script:

define axis/y=20S:5S:1/units=degrees yaxs
define axis/z=0:500:1/units=meters/depth zaxs
SET DATA/EZ/var="lat,depth,temp,salt,o1,o2,dens" r165e.dat

let salinite
=SCAT2GRIDGAUSS_YZ(lat,depth,salt,y[gy=yaxs],z[gz=zaxs],2,2,2,2)

And instead of having a 2-D YZ field for salinite, I got a 3-D i,Y,Z
field, and of course with stupid values.
What's wrong in my script? What didn't I understand?

Thanks a lot for your help,

Sophie









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