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MathGroup Archive 2006

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message question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg70918] message question
  • From: "dimitris" <dimmechan at yahoo.com>
  • Date: Wed, 1 Nov 2006 03:56:18 -0500 (EST)

Consider the following

sols = Solve[x^3 + 2*x^2 - 1 == 0]
{{x -> -1}, {x -> (1/2)*(-1 - Sqrt[5])}, {x -> (1/2)*(-1 + Sqrt[5])}}

Why do they appear the warning messages in the following command?

x^3 + 2*x^2 - 1 == 0 /. sols
N::meprec: Internal precision limit $MaxExtraPrecision =
49.99999999999999` \
reached while evaluating \!\(\(-1\) + 1\/2\ \((\(-1\) - \@5)\)\^2 +
1\/8\ \(\(\((\(-1\) - \
\@5)\)\^3\)\(.\)\)\)
N::meprec: Internal precision limit $MaxExtraPrecision =
49.99999999999999` \
reached while evaluating \!\(\(-1\) + 1\/2\ \((\(-1\) - \@5)\)\^2 +
1\/8\ \(\(\((\(-1\) - \
\@5)\)\^3\)\(.\)\)\)
{True, -1 + (1/2)*(-1 - Sqrt[5])^2 + (1/8)*(-1 - Sqrt[5])^3 == 0, -1 +
(1/2)*(-1 + Sqrt[5])^2 + (1/8)*(-1 + Sqrt[5])^3 == 0}

which they don't avoid the verification

FullSimplify[%]
{True,True,True}

Is it a way to avoid the messages (apart from turn off the message)?

The following seems not to help.

Block[{$MaxExtraPrecision = 1000}, x^3 + 2*x^2 - 1 == 0 /. sols]

Thanks a lot


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