- To: mathgroup at smc.vnet.net
- Subject: [mg23038] Re: [mg23007] Chop?
- From: BobHanlon at aol.com
- Date: Thu, 13 Apr 2000 02:43:24 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Chop is doing exactly what the documentation states it will. Chop uses a default tolerance of 10^-10. Use Chop[expr, delta] to replace numbers smaller in absolute magnitude than delta by 0. Bob Hanlon In a message dated 4/11/2000 11:44:13 PM, rustybel at foothill.net writes: >I have been noticing lately that sometimes Chop does not succeed in >reducing numbers close to 0 to 0. Although my email program scrambled the >superscripts, those '-7's down there are from the 10^-7's where I would >expect (and would want) to see plain 0. Mathematica version 4.01 on a Mac. >Copied >as plain text from OutputForm. > >This failure of Chop has ruined one of my most important algorithms, which >takes the Union of a list of n-vectors. It has wrecked in turn my most >important notebooks. Notice, if you will, members 5 and 6 of the list >below, where the z component should have Chopped to zero, but instead is >two very small numbers of opposite sign. >