Erik Naggum <erik@naggum.no> wrote:
+---------------
| why is the following the wrong solution?
|
| (defmethod mref ((A square-matrix) (i integer) (j integer))
| (+ (mref (slot-value A 'lower-triangle) i j)
| (mref (slot-value A 'upper-triangle) i j)))
+---------------
Hmmm... There's something basically wrong with the whole approach of
the original problem statement that I just noticed in Erik's formulation
of this "mref", namely: In normal matrix algebra, both the lower- and
upper-triangle representations usually *include* the main diagonal, so
if a square-matrix is just a struct of a lower and an upper, a bunch of
constructor-time & mutator-time constraint/consistency stuff is going to
be needed to guarantee that the two diagonals stay consistent!
-Rob
-----
Rob Warnock, 8L-846 rpw3@sgi.com
Applied Networking http://reality.sgi.com/rpw3/
Silicon Graphics, Inc. Phone: 650-933-1673
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