[Gretl-users] autoreg formula and bessel function

Allin Cottrell cottrell at wfu.edu
Mon Jun 15 22:07:52 EDT 2009


On Sun, 14 Jun 2009, Klein, Christoph wrote:

> [F]or my diploma thesis I have added a command to gretl which
> computes the bessel function. The function is implemented using
> the gsl library. I would like to contribute this to gretl, too,
> but I don't know how you feel about linking against gsl?

I have now added the cephes Bessel-function code to the gretl code
base; the relevant functionality is now present in "raw" form.
I'm putting a sample C program plus Makefile in

http://www.wfu.edu/~/cottrell/bessel/

On running the program 'bessel' (which links against libgretl) you
get a set of *.txt data files which can be displayed in gnuplot
using the *.gp files in the same directory.

One could take the sample program as a basis for adding a
gretl_bessel function (maybe to lib/src/genfuncs.c), and then work
out a user interface.

While it may make sense to have dozens of "bessel" functions in
the libgsl API, I think we'd want just one function for gretl's
user-space. Perhaps a three-parameter function, with arguments n
(could be fractional), x, and a code of some sort for the type of
function (J, Y, I, K, etc.).

Allin Cottrell


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