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RE: Re: Insufficient capacity

  • To: mathgroup at smc.vnet.net
  • Subject: [mg86534] RE: [mg86199] Re: Insufficient capacity
  • From: "Tugrul Temel" <temelt at xs4all.nl>
  • Date: Thu, 13 Mar 2008 04:32:42 -0500 (EST)

Dear All,

Thanks for your tips...My problem remains, however.

I have a system of equations stored in Excel. I import the following system
to a Mathematica code without any problem:
(1) Xbm = a vector of N1 real numbers with 20 decimals
(2) equR = a vector of N2 equations in the form: X1 - b X2 = 0 where b is a
20 decimal number. For example, with N2=4, we write equR={X1 - b X2 = 0, X3
- c X5 = 0, X4 - a X3 = 0, X5 - d X4 = 0} where coefficients (a, b, c, d)
each of which has 20 decimals
(3) equI = a vector of N3 equations in the form: Y1 +Y2 - Y3 - Y4 = 0. For
example, with N3=3, we write equI={ Y1 +Y2 - Y3 - Y4 = 0, Y4 - Y6 = 0, Y1 +
Y3 - Y5 =0} 

The actual system I am going to solve has a total of 3,500 unknowns and
3,500 equations (N2+N3=3,500).

I have no problem in importing the data in Excel to Mathematica. My problem
starts when I do several matrix operations because of large decimal numbers.
When I make matrix operations, the Mathematica code is not able to the
operations and puts me out of the program. I suspect two things:

1) my computer does not have enough memory (my computer Intel core 2 duo
processor T5500 has 1.66 Ghz, 667 mhz speed, 2 MB LL cache)
2) large decimals occupy a lot of space in memory
3) Maybe I miss a point in dealing with large decimal numbers.

Please let me know your suggestions about what to do, including having an
upgraded computer with enough memory and speed.

Regards,
Tugrul




-----Original Message-----
From: Alois Steindl [mailto:Alois.Steindl at tuwien.ac.at] 
Sent: Thursday, March 06, 2008 8:55 AM
To: mathgroup at smc.vnet.net
Subject: [mg86534] [mg86199] Re: Insufficient capacity

Hello,
"Tugrul Temel" <temelt at xs4all.nl> writes:

> I transfer large amount of data from Excel to Mathematica v.6 and try to
> do some matrix operations. The size of the matrces are (3500, 3500) with
> 10 digit numbers. However, Mathematica quits when I make the matrix
> operation.
>
> How can I make it possible to do the matrix operations of large sizes? Is
> Grid Math an option in this respect? If so, I like to know how large data
> sets Grid Math can handle?
>
3500x3500 isn't really large.
What are your "matrix operations"?
Does it work, when you convert your matrices to FloatingPoint numbers
(N[matrix])?
Alois






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