Re: Odd behavior?
- To: mathgroup at smc.vnet.net
- Subject: [mg101874] Re: [mg101850] Odd behavior?
- From: DrMajorBob <btreat1 at austin.rr.com>
- Date: Mon, 20 Jul 2009 06:02:22 -0400 (EDT)
- References: <200907191115.HAA20885@smc.vnet.net>
- Reply-to: drmajorbob at bigfoot.com
The version 7 answer is correct. The answer zero assumes infinite precision for the inputs, when in fact they're only "machine" precision. That said, you could use the code 5.1 - 4.5 - 0.6 // Chop 0 This gives infinite precision to a calculation that doesn't deserve it, but then again, it probably does no harm. Bobby On Sun, 19 Jul 2009 06:15:43 -0500, elliot <esadlon at stevens.edu> wrote: > 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. > -- DrMajorBob at bigfoot.com
- References:
- Odd behavior?
- From: elliot <esadlon@stevens.edu>
- Odd behavior?