[Gsll-devel] small modification to blas2.lisp

[Liam Healy]

On Wed, May 14, 2008 at 2:23 PM, Mirko Vukovic <mirko.vukovic at gmail.com> wrote:
> Hi,
>
>  I was playing with gsll and blas.  I modified the cblas-transpose
>  definition in blas2.lisp (see top of file) to capture a few more
>  values:
>
>  Here is the new version:
>
>  (cffi:defcenum cblas-transpose
>   "CBLAS_TRANSPOSE from /usr/include/gsl/gsl_cblas.h."
>   (:notrans 111) (:trans 112) (:conjtrans 113))

I fail to see the difference with what is in there now:
(cffi:defcenum cblas-transpose
  "CBLAS_TRANSPOSE from /usr/include/gsl/gsl_cblas.h."
  (:notrans 111) :trans :conjtrans)
See http://common-lisp.net/project/cffi/manual/html_node/defcenum.html#defcenum
"If value is omitted its value will either be 0, if it's the first
entry, or it it will continue the progression from the last specified
value."
so :trans gets 112, :conjtrans 113 by default.

>
>  I am posting it here because I was not able to download with svn so I
>  don't have versioning for gsll.
>
>  Also, here is a code snippet that I used to test for tridiagonal
>  matrix solving that also uses gsll-s blas2 routine gemv to double
>  check that things work.
>
>  (in-package :gsll)
>  ;; solve a tridiagonal system and then verify result by matrix multiplication
>  ;; uses solve-tridiagonal and gemv
>  (let* ((dim 6)
>        (dim- (- dim 1)))
>   (let ((d (make-array dim :element-type 'double-float :initial-element -2.d0))
>         (e (make-array dim- :element-type 'double-float :initial-element 0.2d0))
>         (f (make-array dim- :element-type 'double-float :initial-element 1.d0))
>         (x (make-array dim :element-type 'double-float :initial-element 0.d0))
>         (b (make-array dim :element-type 'double-float :initial-element 0.5d0))
>         (mat (make-array (list dim dim)
>                          :element-type 'double-float
>                          :initial-element 0.d0)))
>
>     ;; load matrix
>     (loop for i from 0 below dim-
>        do (progn
>             (setf (aref mat i i) (aref d i))
>             (setf (aref mat (+ i 1) i) (aref f i))
>             (setf (aref mat i (+ i 1)) (aref e i))))
>     (setf (aref mat dim- dim-) (aref d dim-))
>
>     ;; gsl operations
>     (letm ((d* (vector-double-float d))
>            (e* (vector-double-float e))
>            (f* (vector-double-float f))
>            (x* (vector-double-float x))
>            (b* (vector-double-float b))
>            (v2* (vector-double-float
>                        (make-array dim :element-type 'double-float
>                                        :initial-element 0.d0)))
>            (mat* (matrix-double-float mat)))
>       (solve-tridiagonal d* e* f* b* x*)
>       ;; gemv returns the result in the last argument
>       (gemv :notrans 1.d0 mat* x* 0.d0 v2*)
>       (data v2*))))
>
>  I am sure this code betrays my lack of lisp experience.  So feel free
>  to clean it up if you want it included in the verification part.
>
>  Mirko

I might make a few simplifications; #'1- to do decrementing and
I don't think there's a need to make arrays in CL and then remake
them on the foreign side.   It is possibly a candidate for
example/ regression tests.

Liam