Timeline for Solve resolves symbolic linear system in 20 seconds, LinearSolve just grinds on and on
Current License: CC BY-SA 3.0
9 events
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Jun 7, 2020 at 16:09 | history | edited | J. M.'s missing motivation♦ |
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Mar 27, 2017 at 16:39 | comment | added | Daniel Lichtblau |
It might be a difference in default setting of Method option to RowReduce .
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Mar 27, 2017 at 5:54 | comment | added | Yair M | Just a thought as I'm no expert. If you think the ZeroTest is the source of the difference use the ZeroTest option to use your own version of ZeroTest, and enforce the two approaches to use the same one, thus checking your hypothesis | |
Mar 27, 2017 at 4:19 | comment | added | user46831 | C.E. Thanks so much for the help! I'm running Mathematica 10.0 and in that version LinearSolve never did come back with an answer, even after several hours. Surprisingly, removing the last variable and equation did the trick. Without those, it solved in 8 seconds. And it's easy to compute that last variable from the answer. J.M. Thanks for the tip. I'll use it! | |
Mar 27, 2017 at 4:03 | history | edited | user46831 | CC BY-SA 3.0 |
Removing the final equation defining a variable that appears in no other equations, resolves the issue. LinearSolve knocks it off in 8 or 9 seconds
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Mar 27, 2017 at 0:50 | comment | added | J. M.'s missing motivation♦ |
BTW: CoefficientArrays[] is an easier way to get the matrix and vector you need: {rhs, matrix} = Normal[CoefficientArrays[equations, variables]]; rhs = -rhs;
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Mar 26, 2017 at 22:34 | comment | added | C. E.♦ |
For me, Solve takes 21 seconds and LinearSolve takes 35 seconds. So LinearSolve is slower, but not that much slower. If I run LinearSolve a second time it returns in 6.3 seconds, due to caching I suppose. Solve takes 19 seconds if I run it a second time, so it does not benefit nearly as much from caching. I'm using Mathematica 11.1.
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Mar 26, 2017 at 22:15 | review | First posts | |||
Mar 26, 2017 at 22:16 | |||||
Mar 26, 2017 at 22:04 | history | asked | user46831 | CC BY-SA 3.0 |