Singularhttp://www.singular.uni-kl.de/forum/ Dealing with big matriceshttp://www.singular.uni-kl.de/forum/viewtopic.php?f=10&t=2559 Page 1 of 1

 Author: lkastner [ Thu Oct 27, 2016 4:24 pm ] Post subject: Dealing with big matrices I am trying to compute Ext for two ideals as follows:Code:ring R = 0,(x(1),x(2),x(3),x(4),x(5),x(6),x(7)),dp;ideal I = x(4)*x(6)-x(3)*x(7),x(5)^2-x(3)*x(7),x(4)*x(5)-x(2)*x(7),x(3)*x(5)-x(2)*x(6),x(1)*x(5)-x(6)*x(7),x(3)*x(4)-x(2)*x(5),x(1)*x(4)-x(5)*x(7),x(1)*x(3)-x(5)*x(6),x(1)*x(2)-x(3)*x(7),x(2)*x(5)*x(6)-x(3)^2*x(7),x(2)^2*x(6)^2-x(3)^3*x(7);qring Q = std(I);ideal D1 = x(7)^2, x(6)*x(7), x(5)*x(7), x(4)*x(7), x(1)*x(7), x(1)*x(6), x(1)^2, x(6)^3, x(5)*x(6)^2, x(4)^3;ideal D2 = x(7)^2, x(4)*x(7), x(4)^2, x(2)*x(5)*x(7), x(2)^2*x(7), x(1)^2*x(7), x(2)^2*x(4), x(2)^3*x(5), x(2)^4, x(1)^4;ideal CminD2 = x(4)^2, x(2)*x(7)^2, x(2)*x(5)*x(7), x(2)*x(4)*x(7), x(2)*x(3)*x(7), x(2)^2*x(7), x(3)*x(7)^3, x(3)^2*x(7)^2, x(3)^3*x(7), x(5)*x(6)*x(7)^3, x(2)*x(3)^2*x(6)^2, x(6)^2*x(7)^4, x(3)^4*x(6)^2;ideal CminD1 = x(6)^3, x(3)*x(6)^2*x(7), x(3)^2*x(6)^2, x(3)^2*x(6)*x(7)^2, x(3)^3*x(6)*x(7), x(3)^4*x(6), x(3)^3*x(7)^3, x(3)^4*x(7)^2, x(3)^5*x(7), x(3)^6, x(2)^2*x(3)*x(6)*x(7)^3, x(2)^2*x(3)^2*x(7)^4, x(2)^4*x(6)*x(7)^4, x(2)^4*x(3)*x(7)^5, x(2)^5*x(5)*x(7)^5, x(2)^6*x(7)^6;LIB "homolog.lib";module M = Ext(5,syz(D1),syz(CminD2));after quite some time this fails with the following error:Code:> module M = Ext(5,syz(D1),syz(CminD2));   ? internal error: creating matrix[7647][38235]Singular : signal 11 (v: 4020):current line:>>   return(matrix(B));<

 Author: hannes [ Mon Oct 31, 2016 5:44 pm ] Post subject: Re: Dealing with big matrices See http://www.singular.uni-kl.de:8002/trac ... 40e01a/git

 Author: lkastner [ Thu Nov 03, 2016 8:05 pm ] Post subject: Re: Dealing with big matrices Thank you. Unfortunately it seems that this was just covering up another bottleneck, which I (and probably you as well) already feared :Code:> module M = Ext(5,syz(D1),syz(CminD2)); Singular error: no more memorySystem 11919379k:17115977k Appl 11905349k/14029k Malloc 11880467k/0k Valloc 38912k/14029k Pages 9453/275 Regions 19:103 Internal: 9808halt 14I will try to find a smaller example.

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