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Groups > comp.soft-sys.math.maple > #254

Re: LinearSolve, BackwardSubstitute(GaussianElimination) - different answers?

From Peter Pein <petsie@dordos.net>
Newsgroups comp.soft-sys.math.maple
Subject Re: LinearSolve, BackwardSubstitute(GaussianElimination) - different answers?
Date 2011-09-26 11:48 +0200
Organization 1&1 Internet AG
Message-ID <j5phq7$62j$1@online.de> (permalink)
References <ea40abbb-3b88-4778-9381-983cb4019475@i28g2000yqn.googlegroups.com>

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Am 26.09.2011 02:46, schrieb lasalle25:
> with(LinearAlgebra):
> a:=<27.6,30.2,162;3100,6400,23610;250,360,1623>;
> LinearSolve(a);
> BackwardSubstitute(GaussianElimination(a));


Hmm...
I get "Error, (in LinearAlgebra:-LA_Main:-BackwardSubstitute) 
inconsistent system"

but using rationals (276/10 and 302/10), the results are the same.
seems to depend on floating point noise

Peter

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Thread

LinearSolve, BackwardSubstitute(GaussianElimination) - different answers? lasalle25 <betty.n.love@gmail.com> - 2011-09-25 17:46 -0700
  Re: LinearSolve, BackwardSubstitute(GaussianElimination) - different answers? acer <maple@rogers.com> - 2011-09-25 20:35 -0700
  Re: LinearSolve, BackwardSubstitute(GaussianElimination) - different answers? Peter Pein <petsie@dordos.net> - 2011-09-26 11:48 +0200
    Re: LinearSolve, BackwardSubstitute(GaussianElimination) - different answers? Ray Vickson <RGVickson@shaw.ca> - 2011-11-04 15:03 -0700

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