[Gsll-devel] gsl_linalg_exponential_ss

[Tamas K Papp]

On Sun, Aug 10, 2008 at 06:38:16PM -0400, Liam Healy wrote:
> Tamas,
> 
> I added this function to the future (ffa) version of GSLL, and
> it works.  This is my attempt at a backport to the current version:
> 
> (defmfun matrix-exponential (matrix exponential)
>   "gsl_linalg_exponential_ss"
>   (((mpointer matrix) :pointer) ((mpointer exponential) :pointer)
>   :mode)
>   :invalidate (exponential)
>   :return (exponential)
>   :documentation
>   "Calculate the matrix exponential by the scaling and
>    squaring method described in Moler + Van Loan,
>    SIAM Rev 20, 801 (1978).  The matrix to be exponentiated
>    is matrix, the returned exponential is exponential.
>    The mode argument allows
>    choosing an optimal strategy, from the table
>    given in the paper, for a given precision.")
> 
> I have not tried it, so try it and see how it works.
> If you give it #2A((0.0d0 1.0d0) (-1.0d0 0.0d0)) it
> should return
> #2A((0.5403023058681384d0 0.841470984807895d0)
>     (-0.841470984807895d0 0.5403023058681384d0))
> i.e., [[cos(1), sin(1)], [-sin(1), cos(1)]]

Hi Liam,

I tried to compile this in the :gsl package (after loading it of
course), and I got the error that mpointer was undefined.

I am more interested in the FFA version of GSLL.  Where can I download
it?

Thanks,

Tamas