[Gsll-devel] need fft routines

[Mirko Vukovic]

I tried recently to link to gsl's gsl_fft_complex_radix2_forward, but
failed miserably:

(defmfun fft-c2f (x n)
 "gsl_fft_complex_radix2_forward"
;; for gsl doc and example see
;; http://www.gnu.org/software/gsl/manual/html_node/Radix_002d2-FFT-routines-for-complex-data.html
 ;; for stride I use the example from sorting.lisp
 (((mpointer x) :pointer) (1 sizet) (n :int))
 :inputs (x)
 :definition :function
 :c-return :success-failure
 :documentation
 "Forward FFT for a complex double radix-2 vector")

#|
;; test run
(let ((arg (make-marray '(complex double-float) :dimensions 4
						:initial-element #c(0d0 0d0))))
  (setf (aref arg 2) #c(1d0 0d0))
  (let* ((dim (length arg)))
;; 	 (double (make-array (* 2 dim)
;; 			     :element-type 'double-float
;; 			     :initial-element 0d0)))
    ;; repackaging complex as double -- is there a built-in? ;
;;     (loop
;;        for re-im across arg
;;        for i from 0 to (* 2 (1- dim)) by 2
;;        do (progn
;; 	    (setf (aref double i) (realpart re-im))
;; 	    (setf (aref double (1+ i)) (imagpart re-im))))
    (print dim)
    (fft-c2f arg dim)))
|#


I see one possible problem, that gsl_complex_packed_array datatypes.
I don't see those defined in gsll.

Can someone help me with linking to the fft routines?  Once I can
access gsl's fft's, I will verify the computation, and also generate
the unit tests.

Thanks,

Mirko