Re: Odd [math] behavior
This WebDNA talk-list message is from 2003
It keeps the original formatting.
numero = 52778
interpreted = N
texte = I cringed when I saw this thread, knowing that it would lead to a discussion of the inaccuracies of binary representation of decimal numbers. I got a kick out of the following quote (taken from one of the links John provided - Thanks, John!). "Floating point is by its nature inexact. It is probably best if you imagined that after every floating point operation, a little demon came in and added or subtracted a tiny number to fuzz the low order bits of your result..." I am sure that even the most experienced programmer has gotten 'bit' by this. So, I think the lesson here is to ALWAYS keep in mind the desired 'precision' when performing floating point arithmetic and use the [format x.xf] to ensure that you get what you expect. FEEDBACK REQUEST: Given that most WebDNA programmers would not expect to have to deal with those 'fuzzy' low order bits, perhaps we should build in a more user-friendly default precision for the MATH context. Maybe have it controlled via a new WebDNA pref? Any thoughts? -----Original Message----- From: John Peacock [mailto:jpeacock@rowman.com] Sent: Thursday, September 11, 2003 12:23 PM To: WebDNA-Talk@talk.smithmicro.com Subject: Re: Odd [math] behaviour Paul Willis wrote: > I fully agree, I don't understand why any calculations or formatting are > required. This is simple subtraction. 6000.4-5300.3 is 700.1 a small > child could do it. > Unfortunately, computers are far stupider than even the smallest child. The advantage of using a computer over a child is that the computer actually does what you tell it to do and does it quickly (no "In a minute Daddy!"). A quick Google yielded a few useful pages: http://www.python.org/doc/current/tut/node14.html http://mindprod.com/jgloss/floatingpoint.html http://www.rwc.uc.edu/koehler/comath/14.html HTH John -- John Peacock Director of Information Research and Technology Rowman & Littlefield Publishing Group 4501 Forbes Boulevard Suite H Lanham, MD 20706 301-459-3366 x.5010 fax 301-429-5748 ------------------------------------------------------------- This message is sent to you because you are subscribed to the mailing list
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I cringed when I saw this thread, knowing that it would lead to a discussion of the inaccuracies of binary representation of decimal numbers. I got a kick out of the following quote (taken from one of the links John provided - Thanks, John!). "Floating point is by its nature inexact. It is probably best if you imagined that after every floating point operation, a little demon came in and added or subtracted a tiny number to fuzz the low order bits of your result..." I am sure that even the most experienced programmer has gotten 'bit' by this. So, I think the lesson here is to ALWAYS keep in mind the desired 'precision' when performing floating point arithmetic and use the [format x.xf] to ensure that you get what you expect. FEEDBACK REQUEST: Given that most WebDNA programmers would not expect to have to deal with those 'fuzzy' low order bits, perhaps we should build in a more user-friendly default precision for the MATH context. Maybe have it controlled via a new WebDNA pref? Any thoughts? -----Original Message----- From: John Peacock [mailto:jpeacock@rowman.com] Sent: Thursday, September 11, 2003 12:23 PM To: WebDNA-Talk@talk.smithmicro.com Subject: Re: Odd [math] behaviour Paul Willis wrote: > I fully agree, I don't understand why any calculations or formatting are > required. This is simple subtraction. 6000.4-5300.3 is 700.1 a small > child could do it. > Unfortunately, computers are far stupider than even the smallest child. The advantage of using a computer over a child is that the computer actually does what you tell it to do and does it quickly (no "In a minute Daddy!"). A quick Google yielded a few useful pages: http://www.python.org/doc/current/tut/node14.html http://mindprod.com/jgloss/floatingpoint.html http://www.rwc.uc.edu/koehler/comath/14.html HTH John -- John Peacock Director of Information Research and Technology Rowman & Littlefield Publishing Group 4501 Forbes Boulevard Suite H Lanham, MD 20706 301-459-3366 x.5010 fax 301-429-5748 ------------------------------------------------------------- This message is sent to you because you are subscribed to the mailing list . To unsubscribe, E-mail to: To switch to the DIGEST mode, E-mail to Web Archive of this list is at: http://webdna.smithmicro.com/ ------------------------------------------------------------- This message is sent to you because you are subscribed to the mailing list . To unsubscribe, E-mail to: To switch to the DIGEST mode, E-mail to Web Archive of this list is at: http://webdna.smithmicro.com/
"Scott Anderson"
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