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MathGroup Archive 1992

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Re: Can Mathematica invert large complex arrays ( 700x700)?---in a timely way that is

  • To: mathgroup at yoda.physics.unc.edu
  • Subject: Re: Can Mathematica invert large complex arrays ( 700x700)?---in a timely way that is
  • From: mek at guinan.psu.edu (Mark E. Kotanchek)
  • Date: Fri, 15 May 92 09:27:18 EDT

Since David Jacobson did all the work of determining a function to  
answer this question:

   Gregory Lampshire asks about the time required to invert a
   700x700 array in Mathematica.
   

   I just did the following on an HP 9000/877 (snakes processor).
   

   In[13]:=
   Timing[Inverse[Table[Random[],{700},{700}]]]//First
   

   Out[13]= 315.05 Second
   

   The Timing command returns a list consisting of the time and the
   answer.  First grabs the time and throws away the answer, since I
   didn't want my screen cluttered with 490000 numbers.
   

   I did this after a whole day of working with mathematica.  It
   pushed the virtual memory consumption up to 50144K.  I'm not
   sure how much I had consumed up to the point where I did this
   example, but it probably wasn't over 15 MB.   

   

I plugged in David's function and ran it on my NeXTstation  
(monochrome, 32 MB RAM) and came out with a result of:

			532.867 Second

I noticed a reasonable amount of disk access during this processing.  
I ran the command a second time with Mathematica as "first responder"  
and "warmed up" and got a result of

			520. Second

So, for what it's worth, enjoy.

Later,

Mark.
---
Mark Kotanchek
Guidance & Control Dept - 363 ASB
Applied Research Lab/Penn State
P.O. Box 30
State College, PA 16804

e-mail:	mek at guinan.psu.edu (NeXTmail)
TEL:	(814)863-0682
FAX:	(814)863-7843





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