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Odd behavior?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg101850] Odd behavior?
  • From: elliot <esadlon at stevens.edu>
  • Date: Sun, 19 Jul 2009 07:15:43 -0400 (EDT)

The expression 5.1 - 4.5 - 0.6 gives different answers depending on the version of Mathematica. Version 6 says 0. (which is obviously what we expect) with an accuracy of about 307. Version 7 says -3.33067x10^-16 with an accuracy of about 31. Also, in version 7, if the expression is changed to 5.1 - (4.5 + 0.6) the answer it gives is 0. with an accuracy of about 307. Both versions were run on three different computers.

Anybody know what changed or what I can do to prevent such poor solutions (besides forcing a specific order of evaluation)? Thanks.


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