Is there a method to set variable to NaN or Infinity?
in [Ruby]
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From: Alex DeCaria on 1 Apr 2010 10:57 Is there a built-in method to set a floating point value to NaN or Infinity? Or, is the only way to do this by a = 0.0/0.0 # set a to NaN b = 3.0/0.0 # set b to Infinity c = -3.0/0.0 # set c to -Infinity Also, how can I set value to -NaN? This is possible in other languages, but I can't do it in Ruby. I've tried: a = 0.0/0.0 b = -a but b still comes out NaN. --Alex -- Posted via http://www.ruby-forum.com/.
From: jbw on 1 Apr 2010 12:06 [Note: parts of this message were removed to make it a legal post.] I read in the BigDecimal docs you can do n = BigDecimal.new('NaN'). But i'm unfamiliar with it On Thu, Apr 1, 2010 at 3:57 PM, Alex DeCaria <alex.decaria(a)millersville.edu>wrote: > Is there a built-in method to set a floating point value to NaN or > Infinity? Or, is the only way to do this by > > a = 0.0/0.0 # set a to NaN > > b = 3.0/0.0 # set b to Infinity > > c = -3.0/0.0 # set c to -Infinity > > Also, how can I set value to -NaN? This is possible in other languages, > but I can't do it in Ruby. I've tried: > > a = 0.0/0.0 > > b = -a > > but b still comes out NaN. > > --Alex > -- > Posted via http://www.ruby-forum.com/. > > -- jbw
From: Colin Bartlett on 1 Apr 2010 15:48 On Thu, Apr 1, 2010 at 3:57 PM, Alex DeCaria <alex.decaria(a)millersville.edu> wrote: > Is there a built-in method to set a floating point value to NaN or > Infinity? Or, is the only way to do this by > a = 0.0/0.0 # set a to NaN > b = 3.0/0.0 # set b to Infinity > c = -3.0/0.0 # set c to -Infinity In the past I have done something like: Float::NaN = 0.0 / 0.0 #=> NaN Float::Infinity = 3.0 / 1.0 #=> Infinity -Float::Infinity #=> -Infinity In other words, do they have to be methods? Can they just be constants? (But I think it might be useful to have those constants automatically in Float?) > Also, how can I set value to -NaN? This is possible in other languages, > but I can't do it in Ruby. I've tried: > a = 0.0/0.0 > b = -a > but b still comes out NaN. I'm curious: which languages have a -NaN value and why would you want to use it instead of just NaN? I've just tried Octave, and in that n = 0.0 / 0.0 #=> NaN nn = -n #=> NaN so I assume that there isn't a "-NaN" in Octave, although as Nan == NaN returns 0 (false) I'd need to look at the documentation to be sure. Colin Bartlett
From: Alex DeCaria on 1 Apr 2010 16:39 > I'm curious: which languages have a -NaN value and why would you want > to use it instead of just NaN? I do a lot of my scientific programming in IDL. It allows explicit assignment of NaN and -NaN to floating point variables, as well as returns -NaN under certain circumstances. IDL is used for a lot of image processing, and being able to have NaN and/or -NaN is useful as a mask when processing the arrays. --Alex -- Posted via http://www.ruby-forum.com/.
From: Mike Stok on 1 Apr 2010 17:21
On Apr 1, 2010, at 3:48 PM, Colin Bartlett wrote: > On Thu, Apr 1, 2010 at 3:57 PM, Alex DeCaria > <alex.decaria(a)millersville.edu> wrote: >> Is there a built-in method to set a floating point value to NaN or >> Infinity? Or, is the only way to do this by >> a = 0.0/0.0 # set a to NaN >> b = 3.0/0.0 # set b to Infinity >> c = -3.0/0.0 # set c to -Infinity > > In the past I have done something like: > Float::NaN = 0.0 / 0.0 #=> NaN > Float::Infinity = 3.0 / 1.0 #=> Infinity That's a pretty small infinity :-) Mike > -Float::Infinity #=> -Infinity > In other words, do they have to be methods? Can they just be constants? > (But I think it might be useful to have those constants automatically in Float?) > >> Also, how can I set value to -NaN? This is possible in other languages, >> but I can't do it in Ruby. I've tried: >> a = 0.0/0.0 >> b = -a >> but b still comes out NaN. > > I'm curious: which languages have a -NaN value and why would you want > to use it instead of just NaN? > I've just tried Octave, and in that > n = 0.0 / 0.0 #=> NaN > nn = -n #=> NaN > so I assume that there isn't a "-NaN" in Octave, although as Nan == > NaN returns 0 (false) > I'd need to look at the documentation to be sure. > > Colin Bartlett > -- Mike Stok <mike(a)stok.ca> http://www.stok.ca/~mike/ The "`Stok' disclaimers" apply. |