[Matlisp-users] Re: Matrix column access

[Jan R. <ja...@ry...>]

>>>>> "Nicolas" == Nicolas Neuss <Nic...@iw...> writes:
 Nicolas> Jan Rychter <ja...@ry...> writes:
[...]
 >> As it is, I'll probably reinvent the wheel and write my own
 >> functions using DCOPY, as you suggested.

 Nicolas> I'm quite sure this is the choice fitting the Matlisp way
 Nicolas> best.  If you indeed want to make it into a generic function,
 Nicolas> it would be nice if you could use my MEXTRACT/MINJECT syntax.
 Nicolas> Probably, the Matlisp authors would also welcome such a
 Nicolas> contribution.

Well, the discussion seems to have died, so I thought I'd contribute
what I use now. It is much faster than my previous macros. Only works
for real matrices for now.

I didn't use DCOPY, because I don't know how to dereference a particular
element in the matrix store, instead of the store itself (C pointers,
anyone?). DCOPY would undoubtedly be much faster, especially for larger
matrices.

Nicolas -- sorry, I didn't use your syntax. I felt it isn't really
compatible with matlisp and I really wanted to do things like
  (setf (column-ref m i) some-vector)

--J.


(defmethod column-ref ((matrix real-matrix) column)
  (let* ((n (nrows matrix))
	 (result (make-real-matrix-dim n 1))
	 (src-store (matlisp::store matrix))
	 (dst-store (matlisp::store result)))
    (declare (type fixnum n)
	     (type (real-matrix-store-type (*)) src-store dst-store))
    (dotimes (i n)
      (declare (type fixnum i))
      (setf (aref dst-store i) (aref src-store (fortran-matrix-indexing i column n))))
    result))


(defmethod (setf column-ref) (value (matrix real-matrix) column)
  (let* ((n (nrows matrix))
	 (src-store (matlisp::store value))
	 (dst-store (matlisp::store matrix)))
    (declare (type fixnum n)
	     (type (real-matrix-store-type (*)) src-store dst-store))
    (dotimes (i n)
      (declare (type fixnum i))
      (setf (aref dst-store (fortran-matrix-indexing i column n)) (aref src-store i)))
    matrix))


(defmethod row-ref ((matrix real-matrix) row)
  (let* ((n (nrows matrix))
	 (m (ncols matrix))
	 (result (make-real-matrix-dim 1 m))
	 (src-store (matlisp::store matrix))
	 (dst-store (matlisp::store result)))
    (declare (type fixnum n m)
	     (type (real-matrix-store-type (*)) src-store dst-store))
    (dotimes (i m)
      (declare (type fixnum i))
      (setf (aref dst-store (fortran-matrix-indexing 0 i 1)) (aref src-store (fortran-matrix-indexing row i n))))
    result))


(defmethod (setf row-ref) (value (matrix real-matrix) row)
  (let* ((n (nrows matrix))
	 (m (ncols matrix))
	 (src-store (matlisp::store value))
	 (dst-store (matlisp::store matrix)))
    (declare (type fixnum n m)
	     (type (real-matrix-store-type (*)) src-store dst-store))
    (dotimes (i m)
      (declare (type fixnum i))
      (setf (aref dst-store (fortran-matrix-indexing row i n)) (aref src-store (fortran-matrix-indexing 0 i 1))))
    matrix))


(defmethod row-ref-transposed ((matrix real-matrix) row)
  (let* ((n (nrows matrix))
	 (m (ncols matrix))
	 (result (make-real-matrix-dim m 1))
	 (src-store (matlisp::store matrix))
	 (dst-store (matlisp::store result)))
    (declare (type fixnum n m)
	     (type (real-matrix-store-type (*)) src-store dst-store))
    (dotimes (i m)
      (declare (type fixnum i))
      (setf (aref dst-store i) (aref src-store (fortran-matrix-indexing row i n))))
    result))