linear interpolation functions in grads-2.0.a5.oga.5

[Arlindo da Silva]

On Wed, Jul 15, 2009 at 3:10 PM, James T. Potemra <jimp at hawaii.edu> wrote:

> I'm running grads-2.0.a5.oga.5 on a 64-bit linux machine and want to do
> a linear
> fit to a time-series.  There appears to be a UDF called "linreg" that is
> included
> in Mike Fiorino's UDF library, but the man page at
> http://opengrads.org/doc/udxt/libmf/
> does not list this function.
>
> Conversely, there is a man page for "*tregr2"* at
> http://opengrads.org/doc/udxt/libbjt/
> as part of Ben-Jei Tsuang's UDF library, but that does not appear in the
> UDC list
> (see list below).
>

Yes, it is there...


>
> ga-> q udf
>
>  User
>  Defined
>  FUNCTION          Short Description                Function at Library
> ---------- -----------------------------------  --------------------------
> tfit       Point  linear regression             f_bjt@^libbjt.gex
> fit        Global linear regression             f_bjt@^libbjt.gex
> tcorr2     Time correlation                     f_bjt@^libbjt.gex
> * tregr2     Point linear regression              f_bjt@^libbjt.gex*
> tmave2     Time averaging w/masking             f_bjt@^libbjt.gex
>


See also the cookbooks, Mike Bosilovich has some recipes covering linear
regressions.

If you are into python,  pygrads includes pylab which makes these sort of
calculations very simple. If you install python's interface to R you can do
real statistics...

There is also a grads interface for matlab which eliminates to read to write
exchange files. (I just realized that I haven't released this yet... Any
interest?)

    Arlindo


   Arlindo






--
Arlindo da Silva
dasilva at alum.mit.edu
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