Re: [R] Inconsistency using seq

2012-06-18 Thread Petr Savicky
On Mon, Jun 18, 2012 at 12:58:13PM -0700, hamoreno wrote: > Hi all, > > Is there any problem of precision when using seq?. For example: > > x<- seq(0,4,0.1) > x[4]=0.3 > > BUT: > > x[4]-0.3=5.551115e-17 > > It means when I use this condition within an if clause, it does not find > values with

Re: [R] Inconsistency using seq

2012-06-18 Thread Henrik Bengtsson
FYI, > isZero <- function(x, neps=1, eps=.Machine$double.eps, ...) { + (abs(x) < neps * eps) + } > x <- seq(from=0, to=4, by=0.1) > isZero(x[4]-0.3) [1] TRUE > isZero(x[4]-0.3, neps=1) [1] TRUE > isZero(x[4]-0.3, neps=0.1) [1] FALSE You could also have called isZero() isValueSmallEnoughForWhatI

Re: [R] Inconsistency using seq

2012-06-18 Thread Jeff Newmiller
actually, you should build your sequences with integers and scale those to get floating point sequences. --- Jeff NewmillerThe . . Go Live... DCN:Basics: ##.#. ##.#. Li

Re: [R] Inconsistency using seq

2012-06-18 Thread Bert Gunter
Nope. round() is not failsafe either. Basically, there is theoretically no way to guarantee immunity to floating point error in conditional comparisons. You need to either switch to integers -- which **are** exactly represented -- or figure out another way. Of course, practically speaking, suffici

Re: [R] Inconsistency using seq

2012-06-18 Thread hamoreno
Thanks everyone... Seems that I will have to use round before seq to make sure everything has the correct precision. -- View this message in context: http://r.789695.n4.nabble.com/Inconsistency-using-seq-tp4633739p4633750.html Sent from the R help mailing list archive at Nabble.com.

Re: [R] Inconsistency using seq

2012-06-18 Thread R. Michael Weylandt
No, this is rather the nature of floating point calculations. You may perhaps be looking for ?all.equal or R FAQ 7.31 (I think that's the one) which is google-able. It's a complicated subject, but those should get you started. Best, Michael On Jun 18, 2012, at 2:58 PM, hamoreno wrote: > Hi

Re: [R] Inconsistency using seq

2012-06-18 Thread Sarah Goslee
Please read R FAQ 7.31. The problem is with your computer (and everyone else's), and has nothing to do with seq(). On Mon, Jun 18, 2012 at 3:58 PM, hamoreno wrote: > Hi all, > > Is there any problem of precision when using seq?. For example: > > x<- seq(0,4,0.1) > x[4]=0.3 > > BUT: > > x[4]-0.3=5

Re: [R] Inconsistency using seq

2012-06-18 Thread Milan Bouchet-Valat
Le lundi 18 juin 2012 à 12:58 -0700, hamoreno a écrit : > Hi all, > > Is there any problem of precision when using seq?. For example: > > x<- seq(0,4,0.1) > x[4]=0.3 > > BUT: > > x[4]-0.3=5.551115e-17 > > It means when I use this condition within an if clause, it does not find > values with 0.