Re: [Help-gsl] gsl_vector_get () return status

[Martin Jansche]

On 1/2/08, Joel J. Adamson <address@hidden> wrote:
> Howdy,
>
> Using gsl_vector_get (), how do I distinguish between an error accessing
> an out-of-range vector element (returns 0 with error checking off) and
> an element that is genuinely 0?
>
> I am programming in Gambit-C (Scheme->C compiler) using the GSL for
> linear algebra.  The gsl_vector and gsl_matrix operations have worked
> really well for me, however I have a unique problem: I need to know when
> to stop assigning vector elements to a vector in Scheme.  If I can
> determine the length of the vector somehow in C, then I could simply
> allocate the length in the Scheme code and stop at that index.  I
> thought to do this with error checking: iterate up the vector elements
> until I reach an out-of-range element, however I have the above
> problem of distinguishing an element 0 from an error code 0.
>
> Is there a way to either (a) determine the length of the vector in C or

Yes, use my_vector->size.

-- mj

> (b) determine the error condition?  Is there some other variable that
> gets set (errno?) when the error occurs?  I'm fairly new to C, and none
> of the books I have adequately explain how to obtain return status (is
> it anything other than the return value of the function?).
>
> Or should I just use the BLAS functions and abandon gsl_vector and
> gsl_matrix?
>
> Thanks for any help you can offer,
> Joel
> --
> Joel J. Adamson
> Biostatistician
> Pediatric Psychopharmacology Research Unit
> Massachusetts General Hospital
> Boston, MA  02114
> (617) 643-1432
> (303) 880-3109
>
> The information transmitted in this electronic communication is intended only
> for the person or entity to whom it is addressed and may contain confidential
> and/or privileged material. Any review, retransmission, dissemination or other
> use of or taking of any action in reliance upon this information by persons or
> entities other than the intended recipient is prohibited. If you received this
> information in error, please contact the Compliance HelpLine at 800-856-1983 
> and
> properly dispose of this information.
>
>
>
>
> _______________________________________________
> Help-gsl mailing list
> address@hidden
> http://lists.gnu.org/mailman/listinfo/help-gsl
>