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MathGroup Archive 2001

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Re: Exact real parts

  • To: mathgroup at smc.vnet.net
  • Subject: [mg31203] Re: [mg31201] Exact real parts
  • From: Adriano Pascoletti <pascolet at dimi.uniud.it>
  • Date: Fri, 19 Oct 2001 03:11:52 -0400 (EDT)
  • References: <200110170935.FAA19694@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

At 5:35 -0400 17-10-2001, DIAMOND Mark R. wrote:
>Is it possible to get Mathematica to provide the exact real parts of
>something like the 3x3 Hilbert matrix?
>
>h = Table[1/(i + j - 1), {i, 3}, {j, 3}];
>Eigenvalues[h]
>
>N and Chop will obviously give their approximations.
>

Mark,

let e=Eigenvalues[h]

then use

ComplexExpand[e, TargetFunctions -> {Re, Im}]

or

Re[ComplexExpand[e]] returns the list of real parts

Im[ComplexExpand[e]] the list of imaginary parts, which is {0,0,0}
for the symmetric matrix h.

Adriano Pascoletti


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