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MathGroup Archive 2004

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Re: Slow LinearSolve.

  • To: mathgroup at smc.vnet.net
  • Subject: [mg49683] Re: Slow LinearSolve.
  • From: Bill Rowe <readnewsciv at earthlink.net>
  • Date: Tue, 27 Jul 2004 07:01:35 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

On 7/26/04 at 4:02 AM, aaronfude at yahoo.com (Aaron Fude) wrote:

>Within 24 hours and counting, Mathematica was not able to solve Ax
>= b for the following A and the following B. Another system does
>this in a matter of seconds. How do make Mathematica do the same? I
>use "LinearSolve[A, b]"

<snip definition of A and b>

Is the other system performing exact aritmetic? Do you really need an exact solution?

$Version

"5.0 for Mac OS X (June 10, 2003)"

Timing[Chop[LinearSolve[N[A], N[b]]]]

{0.010000000000000009*Second, 
  {0.07446350815950518, 
   0.42971490576148197, 
   -0.07819866153722022, 
   0.8882136952406927, 
   -0.7103217579965401, 
   1.5245842254668558, 
   -1.1153191765998371, 
   1.5245842254671313, 
   -0.7103217579969479, 
   0.8882136952410542, 
   -0.07819866153743803, 
   0.4297149057615676, 
   0.07446350815948745}}
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