Re: [Matlisp-users] m.*! not native?

[Jefferson P. <jp...@cs...>]

Tunc,

Thanks for the help and the code.  I'll look at it and see what I can do and
let you all know.  I may post with some questions on optimization, since I
haven't really tried to optimize my code much before.

Re: "covariance normalization":  I don't know if there's an official name
for it, but basically it's an operation on a square matrix A to produce a
new matrix B, where B(x,y) = A(x,y)/sqrt(A(x,x)*A(y,y)).

If A was a covariance matrix, B will be the corresponding correlation
matrix, with 1's on the diagonal and all the other values in the range
[-1,1].  (i.e. B(x,y) is the correlation between variable x and variable y.)

I have implemented it using MATLISP, but it's not optimized at all... I see
how to optimize it now, I think, so hopefully it should speed up a lot.

Thanks!
Jeff


On 2/1/02 4:55 PM, "Tunc Simsek" <si...@ee...> wrote:

> Hi Ray, Jefferson;
> 
> I've played with Allegro 6.0 as follows (I asked it to explain
> the compilation of m.*!):
> 
> (defmethod m.*! ((a real-matrix) (b real-matrix))
> (let* ((nxm (number-of-elements b)))
>   (declare (type fixnum nxm)
>     (optimize (speed 3) (safety 0)))
> 
>   (dotimes (k nxm b)
>     (declare (type fixnum k))
>     (let ((a-val (matrix-ref a k))
>    (b-val (matrix-ref b k)))
> (declare (type real-matrix-element-type a-val b-val)
> (:explain :calls :types :boxing))
> (setf (matrix-ref b k) (* a-val b-val))))))
> 
> 
> and here is what I get:
> 
> ;;; Compiling file C:\usr\gigascale\shift\src\matlisp\src\mtimes.lisp
> ;Examining a (possibly unboxed) call to *_2OP with arguments:
> ;  symeval A-VAL type (DOUBLE-FLOAT * *)
> ;  symeval B-VAL type (DOUBLE-FLOAT * *)
> ; which returns a value of type (DOUBLE-FLOAT * *)
> ;Generating a DOUBLE-FLOAT box
> ;Examining a call to FUNCALL with arguments:
> ;  call to CDR type KNOWN-FUNCTION
> ;  symeval G16043 type (DOUBLE-FLOAT * *)
> ;  symeval G16044 type #<STANDARD-CLASS REAL-MATRIX>
> ;  symeval G16045 type (INTEGER -536870912 536870911)
> ; which returns a value of type T
> ;Examining a call to CDR with arguments:
> ;  constant ((EVAL-WHEN-LOADED) SETF-METHOD-LOCATIVE (QUOTE MATRIX-REF)
> ...) type TRUE-LIST
> ; which returns a value of type KNOWN-FUNCTION
> ;;; Writing fasl file C:\usr\gigascale\shift\src\matlisp\bin\mtimes.fasl
> 
> so my conclusion is that the MATRIX-REF used to access the variables is
> waaaaay more expensive than AREF.  Insomuch that it has the overhead of
> a generic function dispatch and also a boxing of the results.
> This will explain the performance figures given by Jefferson, which
> I was able to duplicate (roughly on the same order) on my Windows 2000
> pentium something machine.
> 
> Now I quickly tried the following change and got a performance increase
> of exactly 10 fold (ie. from 1.7 seconds per call to .13 seconds)
> and the compiler is still saying that there is boxing.  I don't know
> the Allegro flags very well, but it seems that the matlisp sources
> can be modified so that this performance problem disappears
> and there is no need to do m.*! in fortran. (disclaimer:  I DIDN'T
> TEST IF THE FOLLOWING MODIFICATIONS GIVE CORRECT COMPUTATIONAL
> RESULTS OR ARE CONSISTENT WITH MATLISP CODING STANDARDS)
> 
> (defmethod m.*! ((a real-matrix) (b real-matrix))
> (let* ((nxm (number-of-elements b))
> (aa (store a))
> (bb (store b)))
>   (declare (type fixnum nxm)
>     (type (real-matrix-store-type (*)) aa bb)
>     (optimize (speed 3) (safety 0)))
> 
>   (dotimes (k nxm b)
>     (declare (type fixnum k))
>     (let ((a-val (aref aa k))
>    (b-val (aref bb k)))
> (declare (type real-matrix-element-type a-val b-val)
> (:explain :calls :types :boxing))
> (setf (aref bb k) (* a-val b-val))))))
> 
> Good luck and keep this list posted on your results,
> I think a tested version of these changes should be checked in
> to the repository.
> 
>  -- Tunc
> 
> ps. I don't know your terminology on covariance normalization.
> But it seems to me that it should be possible using matlisp functions.
> 
> Jefferson Provost wrote:
>> 
>> On 2/1/02 11:34 AM, "Raymond Toy" <to...@rt...> wrote:
>> 
>>>>>>>> "Jefferson" == Jefferson Provost <jp...@cs...> writes:
>>> 
>>> You are right.  A peek at the generated code on Solaris seems to show
>>> that we are calling out to generic functions way too often and could
>>> be vastly optimized.
>>> 
>>> I know with CMUCL, a Lisp version of m+ was almost as fast (< 5%
>>> slower?) than Fortran, so m.* should be as fast, even in Lisp.
>>> 
>>> I'll look in to it soon.
>> 
>> Thanks, though I'd be happy to just write the thing in fortran myself, but
>> I'm totally unfamiliar with the foreign function interfaces for Allegro and
>> CMUCL.
>> 
>> Actually, I have another routine that I use a lot which I was hoping might
>> be in MATLISP, but which I couldn't find.  I've had to write it myself (in
>> lisp) and it's slower than I'd like it to be.  It's basically the
>> "covariance normalization" i.e. the normalization that turns a covariance
>> matrix into a correlation coefficients matrix.
>> 
>> J.
>> 
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