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Re: The unstable LinearSolve

  • To: mathgroup at
  • Subject: [mg47823] Re: The unstable LinearSolve
  • From: "Qihong Wu" <wu62 at>
  • Date: Wed, 28 Apr 2004 06:56:11 -0400 (EDT)
  • Organization: Purdue University
  • References: <c6icl4$6o2$> <c6l7es$imc$>
  • Sender: owner-wri-mathgroup at

Mariusz, The CPU of Optiplex is Pentium 4, and the laptop is Pentium M.

"Mariusz Jankowski" <mjankowski at> wrote in message
news:c6l7es$imc$1 at
> Qihong, the difference must be due to the computer's processor. I suspect
> the Optiplex uses a Celeron while the laptop has a Pentium 4.
> Mariusz
> >>> Qihong Wu<wu62 at> 4/26/2004 3:10:28 AM >>>
> Hi,  Guys
> I have an amazing question about LinearSolve[A,b].
> There is a 60k*60k complex matrix A in the form of SparseArray, and a
> Complex Vector b, Now I want to solve A X=b by LinearSolve[A,b]. It will
> take ~4 seconds to solve it by my IBM T40 2373-4cu laptop (PM1.5G/512M),
> this is a good result I think as shown in the new features of Mathematica
> 5.
> But the nightmare is that it takes ~50 second to finish it by a Dell
> Optiplex GX 260 2.8GHz/1024M. The Dell speed is almost 10 times slower
> IBM Laptop. Does it make sense under Same platform (Both of them is
> Mathematica 5/Win Xp)? Does anybody has the same experience? Any comments
> are very appreciated.
> Btw: What type should I use for a matrix in the form of SparseArray in the
> Compile function. The elements in the Matrix are complex, when I said
> {A,_Complex,2} in the compile function, Mathematica 5 always said the type
> was wrong. Why? What type should I use in Compile? Thank you.

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