Menu
▾
▴
[Maxima-bugs] [ maxima-Bugs-3494838 ] invert matrix does not work for large matrix
|
From: SourceForge.net <no...@so...> - 2012-03-16 18:13:28
|
Bugs item #3494838, was opened at 2012-02-26 14:10 Message generated for change (Comment added) made by You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3494838&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: None Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: https://www.google.com/accounts () Assigned to: Nobody/Anonymous (nobody) Summary: invert matrix does not work for large matrix Initial Comment: HI I am trying to invert 25x25 matrix. Maxima starts working for 6 hours and I did not get a result. either it is too slow or there is a bug I test my matrix in maple and I got a result in seconds. this what i did M:matrix([1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1],[0,1,0,-1,0,1,-1,-1,1,3,0,-3,0,3,1,-1,-3,-3,-1,1,3,3,-3,-3,3],[0,0,1,0,-1,1,1,-1,-1,0,3,0,-3,1,3,3,1,-1,-3,-3,-1,3,3,-3,-3],[0,1,0,1,0,1,1,1,1,9,0,9,0,9,1,1,9,9,1,1,9,9,9,9,9],[0,0,1,0,1,1,1,1,1,0,9,0,9,1,9,9,1,1,9,9,1,9,9,9,9],[0,0,0,0,0,1,-1,1,-1,0,0,0,0,3,3,-3,-3,3,3,-3,-3,9,-9,9,-9],[0,1,0,-1,0,1,-1,-1,1,27,0,-27,0,27,1,-1,-27,-27,-1,1,27,27,-27,-27,27],[0,0,0,0,0,1,1,-1,-1,0,0,0,0,9,3,3,9,-9,-3,-3,-9,27,27,-27,-27],[0,0,0,0,0,1,-1,-1,1,0,0,0,0,3,9,-9,-3,-3,-9,9,3,27,-27,-27,27],[0,0,1,0,-1,1,1,-1,-1,0,27,0,-27,1,27,27,1,-1,-27,-27,-1,27,27,-27,-27],[0,1,0,1,0,1,1,1,1,81,0,81,0,81,1,1,81,81,1,1,81,81,81,81,81],[0,0,0,0,0,1,-1,1,-1,0,0,0,0,27,3,-3,-27,27,3,-3,-27,81,-81,81,-81],[0,0,0,0,0,1,1,1,1,0,0,0,0,9,9,9,9,9,9,9,9,81,81,81,81],[0,0,0,0,0,1,-1,1,-1,0,0,0,0,3,27,-27,-3,3,27,-27,-3,81,-81,81,-81],[0,0,1,0,1,1,1,1,1,0,81,0,81,1,81,81,1,1,81,81,1,81,81,81,81],[0,0,0,0,0,1,1,-1,-1,0,0,0,0,81,3,3,81,-81,-3,-3,-81,243,243,-243,-243],[0,0,0,0,0,1,-1,-1,1,0,0,0,0,27,9,-9,-27,-27,-9,9,27,243,-243,-243,243],[0,0,0,0,0,1,1,-1,-1,0,0,0,0,9,27,27,9,-9,-27,-27,-9,243,243,-243,-243],[0,0,0,0,0,1,-1,-1,1,0,0,0,0,3,81,-81,-3,-3,-81,81,3,243,-243,-243,243],[0,0,0,0,0,1,1,1,1,0,0,0,0,81,9,9,81,81,9,9,81,729,729,729,729],[0,0,0,0,0,1,-1,1,-1,0,0,0,0,27,27,-27,-27,27,27,-27,-27,729,-729,729,-729],[0,0,0,0,0,1,1,1,1,0,0,0,0,9,81,81,9,9,81,81,9,729,729,729,729],[0,0,0,0,0,1,1,-1,-1,0,0,0,0,81,27,27,81,-81,-27,-27,-81,2187,2187,-2187,-2187],[0,0,0,0,0,1,-1,-1,1,0,0,0,0,27,81,-81,-27,-27,-81,81,27,2187,-2187,-2187,2187],[0,0,0,0,0,1,1,1,1,0,0,0,0,81,81,81,81,81,81,81,81,6561,6561,6561,6561]); invert(M); I am using Maxima 5.26.0 on windows 7 regards ---------------------------------------------------------------------- >Comment By: https://www.google.com/accounts () Date: 2012-03-16 11:13 Message: also M^^-1; works fine for me even with symbolic matrix; but also this command wont work for a 36x36 matrix ---------------------------------------------------------------------- Comment By: Barton Willis (willisbl) Date: 2012-02-29 00:44 Message: Another workaround is to use invert_by_lu: (%i11) invert_by_lu(M)$ Evaluation took 0.2000 seconds (0.2000 elapsed) (%i12) invert(M), ratmx : true$ Evaluation took 3.4700 seconds (3.4700 elapsed) The slowness of invert(M) with ratmx : false is, I think, a bug. ---------------------------------------------------------------------- Comment By: https://www.google.com/accounts () Date: 2012-02-26 17:24 Message: thanks that works if there is a way to implement a function that switch this option on when dealing with large matrix instead of hangout for hours it will be better. regards ---------------------------------------------------------------------- Comment By: Barton Willis (willisbl) Date: 2012-02-26 14:59 Message: Try setting ratmx : true. The inversion takes about 3.48 seconds on my machine. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3494838&group_id=4933 |