Konstantin L. Metlov wrote:
Hello !
I'm looking for possibilities to plug a Fortran numerical integration routines
into J to be able to evaluate numerical quadratures efficiently. This is
especially needed for multi-dimensional integrals, requiring an adaptive
sub-division of integration region, which is alredy implemented very
efficiently in Fortran (for one-dimensional case I wrote a simple
Jacobi-Gauss quadrature in pure tacit J, which is fast enough and allows for
endpoint singularities).
What I'm missing is the possibility to pass a pointer to the integrand
function (written in J) into the Fortran or C code (called from J).
I've seen the lab on callbacks, but they are only allowed to return a scalar
integer result, while I'd like to be able to receive and pass back to Fortran
(or C) a vector (of floats) or, even better, a general array. Is there another
interface for writing external (defined in DLLs) adverbs (or conjunctions),
taking a function (verb) as an argument ?
Thank you !
With the best regards,
Konstantin.
Hi Konstantin,
You might take a look at: http://www.jsoftware.com/jwiki/Interfaces/Fortran and
http://www.jsoftware.com/jwiki/Packages/LBFGS . These discusses one technique
of interfacing Fortran subroutines to J.
In particular, the lbfgsb routine is designed in a co-routine style that allows
the J code to test the results of the Fortran routine and then return to Fortran
for further processing. The data passed back and forth between J and Fortran
consists of a boxed list of scalars and vectors, of floats, ints and chars.
All the best,
David Mitchell
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