Larger matrices
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From: amado.alves on 6 Aug 2008 09:32 I manage to process 1000 x 1000 matrices with the respective Ada 2005 standard library with GNAT GPL 2008. Processing includes multiplication by a vector. Now I want larger matrices, say 5000 x 5000. The objects seem to be allocated ok (dynamically), but mutiplication gives a "segmentation fault." Any tips on how to overcome this? Thanks a lot.
From: Georg Bauhaus on 6 Aug 2008 10:29 amado.alves(a)gmail.com schrieb: > Now I want larger matrices, say 5000 x 5000. The objects seem to be > allocated ok (dynamically), but mutiplication gives a "segmentation > fault." > > Any tips on how to overcome this? Have you tried having gnatmake recompile the library units (-a,-f,-s) with, say, -g, -O, -gnata, -gnato, and -fstack-check? Might yield a better diagnostic. -- Georg Bauhaus Y A Time Drain http://www.9toX.de
From: amado.alves on 6 Aug 2008 11:01 > Have you tried having gnatmake recompile the library > units (-a,-f,-s) with, say, -g, -O, -gnata, -gnato, > and -fstack-check? Might yield a better diagnostic. (Bauhaus) I'll try that and let you all know. Thanks a lot for this great first orientation in the miriad set of compiler options.
From: amado.alves on 6 Aug 2008 13:29 It's a Storage_Error with the message "stack overflow detected". My program does not use the stack, so probably the multiplication is implemented as a function with parameters passed on the stack and this overflows, like it does if I trie to create the large arrays as static objects. Next I will try to increase the stack size, but I bet I'm gonna hit the 2G ceiling :-( (Recently I saw memory pointers being defined as 32-bit integers.)
From: Dmitry A. Kazakov on 6 Aug 2008 13:58
On Wed, 6 Aug 2008 10:29:09 -0700 (PDT), amado.alves(a)gmail.com wrote: > It's a Storage_Error with the message "stack overflow detected". > > My program does not use the stack, so probably the multiplication is > implemented as a function with parameters passed on the stack and this > overflows, like it does if I trie to create the large arrays as static > objects. IMO, for such huge matrices and vectors, it is better to use in-place operations, rather than a loose functional programming style. And do you have dense 5000 x 5000 matrices? You are a hardworking man! (:-)) -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de |