Re: m.*! not native?

On 2/1/02 7:28 AM, "Raymond Toy" <[email protected]> wrote:


>   Jefferson> D = 1x500 real matrix
> 
> You do realize that a*b is O(500^3), a+b is O(500^2) and c*d is also
> O(500^2).  So it's not surprising that a*b takes 157 times longer than
> a+b and 88 times longer than c*d.

Yes, I realize that.  But I wasn't doing a*b, I was doing a.*b, which is
O(500x500), same as a+b, and c*d.

Looking in mtimes.lisp, m* is implemented by calling GEMM, which is
implemented in fortran, but  m.* and m.*! are written in lisp.  It doesn't
surprise me that the routines written in LISP are much slower.  I was just
surprised to find that function written in lisp.

I have to problem writing in myself, but I wanted to make sure I wasn't
missing something first.

J.