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RE: Table through zero...strange

  • To: mathgroup at smc.vnet.net
  • Subject: [mg67032] RE: [mg66988] Table through zero...strange
  • From: "David Park" <djmp at earthlink.net>
  • Date: Wed, 7 Jun 2006 05:10:16 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

It's those pesky binary computers combined with approximate numbers!

Use an exact calculation and then convert it to approximate numbers (it has
no problem with an exact zero)

Table[x, {x, -1/10, 0, 1/50}]
% // N
{-(1/10), -(2/25), -(3/50), -(1/25), -(1/50), 0}
{-0.1, -0.08, -0.06, -0.04, -0.02, 0.}

or, use the Mathematica Chop function.

Table[x, {x, -0.1, 0, 0.02}] // Chop
{-0.1, -0.08, -0.06, -0.04, -0.02, 0}

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/



From: leptonic [mailto:leptonic at gmx.ch]
To: mathgroup at smc.vnet.net


Hello,

When i type in Mathematica (version 4) Table[x, {x, -0.1, 0, 0.02}]

it gives me {-0.1, -0.08, -0.06, -0.04, -0.02, -3.46945 x 10-18]}
but for example Table[x, {x, -0.1, 0, 0.05}] will give a reasonable
{-0.1, -0.05, 0.}.

Probably a very stupid question but i can't figure out why the zero
makes problem.

Thanks for any help.



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