[Gsll-devel] Extracting sub-matrices and sub-vectors?

[Malcolm Reynolds]

Hi guys,

I've been out of the country for a while but I'm getting back to work
on my project. Something else I've been wondering about for GSLL is
whether there is a way to quickly extract sub-matrices and especially
sub-vectors from a matrix. Something with power equivalent to the
matlab indexing using a colon to express ranges would be amazing but I
guess probably quite nasty to implement efficiently. However, what
would help me even more right now is a way to extract rows / columns
from a matrix, without copying. I currently use a do-loop to run
through the indices I want, but since the internals of the storage
appear to be row major, is there a way to get a "pointer" (not sure if
this is preferred lisp terminology, sorry) to an individual row?

To clarify, if I do

(defvar x (make-marray 'double-float :initial-contents '((1 2 3) (4 5
6) (7 8 9))))

is there any efficient way (ie don't need to copy element by element
to a new object) thatI can get a reference to the row (4 5 6) of that,
either as a gsll::matrix or gsll::vector object? If structure was
shared between the matrix and the vector that would be no problem, it
would be ideal in fact.

Regards

Malcolm

Malcolm