uBLAS Observation: terrible execution speed for prod(matrix,prod(matrix,prod(matrix,matrix)))

From: Walter Bowen (yg-boost-users_at_[hidden])
Date: 2002-07-29 13:13:33

Hi,
    I am new to uBLAS.  I am looking to see if it will be useful for my
application (I develop 6-Degrees-of-freedom flight simulations used to
analyze avionics systems.)  I have benchmarked a few lines of code with
RogueWave's Math.h++ (testing for execution speed) and made the
following observation.

Observation 1)  For matrix products of two small (~3-by-3) matrices (
i.e., prod(smallMat1, smallMat2) ) uBLAS executes MUCH FASTER than
Math.h++.

Observation 2) For matrix produces of two large matrices (100 by 100)
uBLAS and Math.h++ give similar execuation speed.

Obervation 3) (This is the kicker...) for strung-together matrix
products like "Mat1 * Mat2 * Mat3 * Mat4 * Mat5", which I am
implementing as
"prod(Mat1, prod(Mat2, prod( Mat3, prod(Mat4,Mat5) )  ) ) Math.h++ is
MUCH MUCH FASTER than uBLAS.   -- by ~2 orders OF MAGNITUDE!  I believe
that this is a characteristic of the scalability of template
expressions.

My question is this:  Is there a way I an instruct uBLAS not to use
template expressions when for  strung-together matrix products?

Regards,
    Walt