Re: Odd [math] behavior
This WebDNA talk-list message is from 2003
It keeps the original formatting.
numero = 52788
interpreted = N
texte = If we did add a new pref, it would default to 'disabled' so as not to break any existing code. If one chose to enable it, they would need to handle any side effects. >What if you allowed a Format specification in the Math context? Well....that IS what the [format] context is for. I generally see nothing wrong with redundancy, just that adding new parameters does cost more parsing overhead. WebDNA...LEAN and MEAN ;) -----Original Message----- From: Brian Fries [mailto:webdna@brainscansoftware.com] Sent: Thursday, September 11, 2003 1:44 PM To: WebDNA-Talk@talk.smithmicro.com Subject: Re: Odd [math] behavior What if you allowed a Format specification in the Math context? [math format=1.2f]17/7[/math] This could be combined with an OPTIONAL default precision pref, but I wouldn't want an upgrade installation to break any of my existing math, some of which is pretty complicated and needs a high precision. - brian On Thursday, September 11, 2003, at 01:15 PM, Scott Anderson wrote: > > 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 ------------------------------------------------------------- This message is sent to you because you are subscribed to the mailing list
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If we did add a new pref, it would default to 'disabled' so as not to break any existing code. If one chose to enable it, they would need to handle any side effects. >What if you allowed a Format specification in the Math context? Well....that IS what the [format] context is for. I generally see nothing wrong with redundancy, just that adding new parameters does cost more parsing overhead. WebDNA...LEAN and MEAN ;) -----Original Message----- From: Brian Fries [mailto:webdna@brainscansoftware.com] Sent: Thursday, September 11, 2003 1:44 PM To: WebDNA-Talk@talk.smithmicro.com Subject: Re: Odd [math] behavior What if you allowed a Format specification in the Math context? [math format=1.2f]17/7[/math] This could be combined with an OPTIONAL default precision pref, but I wouldn't want an upgrade installation to break any of my existing math, some of which is pretty complicated and needs a high precision. - brian On Thursday, September 11, 2003, at 01:15 PM, Scott Anderson wrote: > > 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 ------------------------------------------------------------- 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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