How does MATLAB exploit matrix multiplication's associativity?
in [Matlab]
|
From: Merciadri Luca on 18 Jun 2010 13:19 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi, How does MATLAB exploit matrix multiplication's associativity? Given A B C such that their product is possible (in matrix terms), it often happens that complexity(A(BC)) != complexity((AB)C). So, how does MATLAB guess this? Is there a well-known algorithm about this? Thanks. - -- Merciadri Luca See http://www.student.montefiore.ulg.ac.be/~merciadri/ - -- Give a man a fish and you feed him for a day; teach a man to fish and you feed him for a lifetime. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Processed by Mailcrypt 3.5.8 <http://mailcrypt.sourceforge.net/> iEYEARECAAYFAkwbqrgACgkQM0LLzLt8MhxNbwCfY3RjXzlwKt/qwhw4nzWwdc7G u1QAoJyztCDXqAOw3RzvPl9IMO8thR3b =dxzd -----END PGP SIGNATURE-----
From: us on 18 Jun 2010 13:42 Merciadri Luca <Luca.Merciadri(a)student.ulg.ac.be> wrote in message <878w6cuukn.fsf(a)merciadriluca-station.MERCIADRILUCA>... > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Hi, > > How does MATLAB exploit matrix multiplication's associativity? Given A > B C such that their product is possible (in matrix terms), it often > happens that > complexity(A(BC)) != complexity((AB)C). > > So, how does MATLAB guess this? Is there a well-known algorithm about > this? > > Thanks. > - -- > Merciadri Luca > See http://www.student.montefiore.ulg.ac.be/~merciadri/ > - -- > > Give a man a fish and you feed him for a day; teach a man to fish > and you feed him for a lifetime. > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.9 (GNU/Linux) > Comment: Processed by Mailcrypt 3.5.8 <http://mailcrypt.sourceforge.net/> > > iEYEARECAAYFAkwbqrgACgkQM0LLzLt8MhxNbwCfY3RjXzlwKt/qwhw4nzWwdc7G > u1QAoJyztCDXqAOw3RzvPl9IMO8thR3b > =dxzd > -----END PGP SIGNATURE----- this has been discussed at length in this NG... search for stuff like - matrix - multiplication us
From: Bruno Luong on 18 Jun 2010 13:43 Merciadri Luca <Luca.Merciadri(a)student.ulg.ac.be> wrote in message <878w6cuukn.fsf(a)merciadriluca-station.MERCIADRILUCA>... > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Hi, > > How does MATLAB exploit matrix multiplication's associativity? Given A > B C such that their product is possible (in matrix terms), it often > happens that > complexity(A(BC)) != complexity((AB)C). > > So, how does MATLAB guess this? Is there a well-known algorithm about > this? That's a good question. But Matlab does not guess, the expression is just evaluated dumbly from left to right, e.g., A*B*C*D = ((A*B)*C)*D It is up to user to put the parenthesis at his/her will. Bruno
From: Bruno Luong on 18 Jun 2010 16:29 "Bruno Luong" <b.luong(a)fogale.findmycountry> wrote in message <hvgb7a$5u4$1(a)fred.mathworks.com>... > > > > So, how does MATLAB guess this? Is there a well-known algorithm about > > this? It seems Wikipedia page gives a broad enough overview with few relevant papers on the bottom: http://en.wikipedia.org/wiki/Matrix_chain_multiplication Bruno
From: Merciadri Luca on 18 Jun 2010 17:22 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Thanks all. Well, I thought that The Mathworks would have implemented such schemes into MATLAB! - -- Merciadri Luca See http://www.student.montefiore.ulg.ac.be/~merciadri/ - -- It is better to die on one's feet than live on one's knees. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Processed by Mailcrypt 3.5.8 <http://mailcrypt.sourceforge.net/> iEYEARECAAYFAkwb448ACgkQM0LLzLt8MhxIOwCeItbmY46mbZiyNQdiasACKzJO kCIAnRBWLXInBOTUBQkbNyx1kOzZ2Iaq =QgAu -----END PGP SIGNATURE-----
|
Next
|
Last
Pages: 1 2 3 4 5 Prev: error when using "imshow" within a "parfor" loop Next: Simulink 3D Animation Joystick |