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MathGroup Archive 2007

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Re: Eigenvalues

  • To: mathgroup at smc.vnet.net
  • Subject: [mg77745] Re: Eigenvalues
  • From: dh <dh at metrohm.ch>
  • Date: Fri, 15 Jun 2007 06:22:15 -0400 (EDT)
  • References: <f4tjee$fqh$1@smc.vnet.net>


Hi,

you are using integer or rational arithmetic. What you get is an 

algebraic number expressed as root of a polynomial.

If you want to use computer numbers, your imput must contain computer 

numbers. You may e.g. wrap your input in N[..].

Hope this helps, Daniel



amitsoni.1984 at gmail.com wrote:

> Hi,

> 

> I am using Eigenvalues[S] to find the eigenvalues of a matrix. When S

> is a non singular matrix(size 500X500), the result comes very fast and

> I get numerical values of the eigenvalues. When S is singular, or very

> close to singular, the same command takes a very long time and I get

> the solution in the following form:

> ------------------------------------------

> (Root[1 -

> 685943599676205704518784329322181239368381737604683300823488051563928004

> 00 #1 +

> 422683709458129987020719509512322527334828765466847787730553472756576

> 3506258708383447822509137758993927488132783442108014806593541358448555767500

> #1^2 -

> 4756334945955210795836139142803033950863408883091629073980127621488009

> 953862277690213957742565926625592512302479312067202413373431157721376895723657

> 92383917222956224461254901373715676847804396794660504978304000000

> #1^3 +

> 149043931613976872173805300357234123824177187156376686486092172926647734083521

> 317893308585359969916780878974219953919649726995574191854952913882459023542023

> 1375808689867514677371127 ..........

> -------------------------------------------------------------

> 

> How can I get the solution(eigenvalues) as numerical values?

> 

> Thank you,

> Amit

> 

> 




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