Re: interpolation/regridding question

[Brent A McDaniel <gte328r@xxxxxxxxxxxxxxxxxxxxx>]

I should have been more clear.  I am looking for ways to interpolate the
1-17 data to the new axis.  I had wanted to use something more
sophisticated than linear interpolation, preferably a cubic spline
technique, but it appears that linear interpolation is the only one
available through ferret.  Has anyone written a cubic spline external
function?


Thanks for the responses Emilio and Ansley,

Cheers,

-Brent

On Fri, 11 May 2001, Ansley Manke wrote:

> Hi Emilio, and Brent,
> That depends on what one wants of course.   There is also @AVE which
> does a weighted regridding.
>
> Emilio Mayorga wrote:
>
> > Brent,
> >
> > Use @ASN instead of @LIN. It replaces the elements of the old axis with
> > those of the new one, following the order you've specified. You might want
> > to include an explicit time origin in the axis my_time, with the
> > qualifier /T0=
> >
> > I just used @ASN yesterday for the first time and it worked like a charm.
> >
> > Emilio
> >
> > On Fri, 11 May 2001, Brent A McDaniel wrote:
> >
> > >
> > > Hi Ferreters,
> > >
> > > I have a series of 17 3-d grids contained in 1 file with the 4th dimension
> > > being time running from 1 - 17 days.  I want to regrid the data so that
> > > the time axis isn't {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17} but
> > > {1.00, 3.13, 5.25,
> > > 7.38,9.50,11.63,13.75,15.88,18.00,18.38,18.75,19.13,19.50,19.88,20.25,20.63,21.0}.
> > > The variable in the files is called ao.
> > >
> > > From inside ferret I type show transformations and saw @LIN        lin. interp.
> > > which sounds promising but when I checked the manual I didn't find it.
> > > And searching the mail archives for @lin didn't work.
> > >
> > > Is it as simple as something like:
> > >
> > > define axis/units=days my_time = { all those numbers}
> > > let aonew=ao[gt=my_time@LIN]
> > >
> > > ??
> > >
> > >
> > > Thanks.
> > >
> > > - Brent
> > > --
> > > Brent A. McDaniel
> > >
> > > Dept of Earth and Atmospheric Sciences
> > > Georgia Institute of Technology
> > > Atlanta, Ga.  USA
> > >
> > >
> > >
>
> --
> Ansley Manke  Pacific Marine Environmental Laboratory  Seattle WA  (206)526-6246
>
>

-- 
Brent A. McDaniel

Dept of Earth and Atmospheric Sciences
Georgia Institute of Technology
Atlanta, Ga.  USA