From help-octave-request at bevo dot che dot wisc dot edu Wed Dec 17 18:12:16 2003 Subject: Re: Octave QR factorization From: Ross Vandegrift To: "John W. Eaton" Cc: taltman at lbl dot gov, Bart Vandewoestyne , help-octave@bevo.che.wisc.edu Date: Wed, 17 Dec 2003 19:09:55 -0500 On Wed, Dec 17, 2003 at 02:40:34PM -0600, John W. Eaton wrote: > If Matlab gets it "right" on x86 hardware, then perhaps it does not > use the internal 80-bit register operations. Does anyone know of a > way to do that with gcc without using -ffloat-store? (I'd rather not > use -ffloat-store by default due to the potential performance > penalty.) Someone should check on an Intel machine first. I recently built Octave for my system, and all the dependencies, and there's a huge warning in the ATLAS library against using 3DNow! The README claims that the floating point in AMD processors isn't 100% IEEE and that enabling 3DNow! in ATLAS can cause numerical problems. I wonder if this is the cause? The script does fail on my AMD Thunderbird, but I ignored the ATLAS warnings and build with 3DNow - burning speed was more important to me ::-) -- Ross Vandegrift ross at willow dot seitz dot com A Pope has a Water Cannon. It is a Water Cannon. He fires Holy-Water from it. It is a Holy-Water Cannon. He Blesses it. It is a Holy Holy-Water Cannon. He Blesses the Hell out of it. It is a Wholly Holy Holy-Water Cannon. He has it pierced. It is a Holey Wholly Holy Holy-Water Cannon. He makes it official. It is a Canon Holey Wholly Holy Holy-Water Cannon. Batman and Robin arrive. He shoots them. ------------------------------------------------------------- Octave is freely available under the terms of the GNU GPL. Octave's home on the web: http://www.octave.org How to fund new projects: http://www.octave.org/funding.html Subscription information: http://www.octave.org/archive.html -------------------------------------------------------------