Re: The unstable LinearSolve

*To*: mathgroup at smc.vnet.net*Subject*: [mg47823] Re: The unstable LinearSolve*From*: "Qihong Wu" <wu62 at purdue.edu>*Date*: Wed, 28 Apr 2004 06:56:11 -0400 (EDT)*Organization*: Purdue University*References*: <c6icl4$6o2$1@smc.vnet.net> <c6l7es$imc$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Mariusz, The CPU of Optiplex is Pentium 4, and the laptop is Pentium M. Qihong "Mariusz Jankowski" <mjankowski at usm.maine.edu> wrote in message news:c6l7es$imc$1 at smc.vnet.net... > 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 purdue.edu> 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 than > 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. > > > >