Larger matrices
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From: Georg Bauhaus on 7 Aug 2008 02:30 amado.alves(a)gmail.com wrote: > I continue interested in ways to augment the stack size (or another > way) to enable use of the standard library. Not so much for speed, but > more for validation (GNAT passes ACATS right? Are ACATS for this > library setup yet?) Have you tried using ulimit or some such?
From: Dmitry A. Kazakov on 7 Aug 2008 03:44 On Wed, 6 Aug 2008 11:40:09 -0700 (PDT), amado.alves(a)gmail.com wrote: >> IMO, for such huge matrices and vectors, it is better to use in-place >> operations, rather than a loose functional programming style. > > You mean a procedure with out parameter instead of function? in out. For example: procedure Multiply (Accumulator : in out Real_Matrix; Multiplicand : Real_Matrix); > Is there such utility? You mean in the standard library. Unfortunately no, which limits its usability. But you could implement them, as well as frequent mixed cases like: A := A * B + C >> And do you have dense 5000 x 5000 matrices? You are a hardworking man! > > It's an hypertext. An incidence matrix? I believe there exist special methods for representation and handling them. But sorry, my numerical methods is quite outdated. > So now I want to increase the stack size. To 200M. Ooch, that is a bad, bad idea. Stack is not for that. It should take no longer than 5 min to implement Multiply in order that it would use O(n) of pool instead of O(n**2) of stack... -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de
From: amado.alves on 7 Aug 2008 04:01 I tried a few tricks for stack size but failed. I did not find clear documentation. Still interested. In the meanwhile, I did a modification of the library. It is interesting. For matrix by vector multiplication, we have the useful property that | A1 | x B = | A1 x B | | A2 | | A2 x B | |... | | ... | so I am using this property to feed the BLAS function piecemeal. /* And Ada got in the way: slicing restricted to one-dimensional arrays! La donna è mobile! */
From: Egil Høvik on 7 Aug 2008 04:55 In Gnat, the default stack size (for the environmental task, and tasks without a specified Storage_Size) is 2MB (at least for the targets I have looked at). If you're using version 5.04 or higher, you can tell gnatbind to use a different default stack size: -dnn[k|m] Default primary stack size = nn [kilo|mega] bytes -Dnn[k|m] Default secondary stack size = nn [kilo|mega] bytes if you're using gnatmake, take a look at -bargs for how to specify binder options -- ~egilhh
From: johnscpg on 7 Aug 2008 07:28
amado.al...(a)gmail.com wrote: > Upon failing miserably to convince GNAT to use a stack of 200M, I am > currently working around the problem by writing my own matrix-by- > vector multiplication function. It takes 2 seconds for a 5000 x 5000 > matrix, but it does not explode. > > I continue interested in ways to augment the stack size (or another > way) to enable use of the standard library. Not so much for speed, but > more for validation (GNAT passes ACATS right? Are ACATS for this > library setup yet?) > > Thanks a lot. I'm not sure if this relevant to your problem, but when I get segmentation fault in linux, its usually due to insufficient stack mem in the shell I'm in. Read up on: ulimit for bash shell. I use bash, and the command is ulimit -s <some number of Megs>. I get lazy and type ulimit -s unlimited For csh I seem to recall its: limit stacksize unlimited. in BASH: ulimit -s unlimited (type "ulimit -s" to see stack setting. The "s" is for stack.) (type "ulimit -a" to see all settings.) in CSH try: limit stacksize unlimited limit datasize unlimited (type "limit" to see settings.) jonathan |