similar to: Dangerous Bug with IF function of R

Dear R Helpers, I am trying to extract the modulus from divisions by a sequence of fractions. I noticed that %% seems to behave inconsistently (to my untutored eye), thus: > 0.1%%0.1 [1] 0 > 0.2%%0.1 [1] 0 > 0.3%%0.1 [1] 0.1 > 0.4%%0.1 [1] 0 > 0.5%%0.1 [1] 0.1 > 0.6%%0.1 [1] 0.1 > 0.7%%0.1 [1] 0.1 > 0.8%%0.1 [1] 0 > 0.9%%0.1 The modulus for 0.1, 0.2, 0.4 and 0.8 is

Dear all, I am totally confused by the following R output, but don't have a clue for it. > a <- 1 - 0.2 > a == 0.8 [1] TRUE > a <- 1 - 0.8 > a == 0.2 [1] FALSE > a <- 1 - 0.5 > a == 0.5 [1] TRUE > a <- 1 - 0.6 > a == 0.4 [1] TRUE > a <- 1 - 0.9 > a == 0.1 [1] FALSE My R version is Windows XP R version 2.8.1 (2008-12-22).

Hi, I'm using the '%%' operator in some code, and am running into the following erroneous outcome: > 1.2 %% 0.2 [1] 0.2 Unless I'm very mistaken, the result should be 0 (indeed, 12 %% 2 does result in 0). Furthermore: > 1.20000000000000001 %% 0.2 [1] 0.2 > (1.2+1e17) %% .2 [1] 0 Warning message: probable complete loss of accuracy in modulus (Warning

Hi, Today I was flabbergasted to see something that looks like a rounding error in the very basic seq function in R. > a = seq(0.1,0.9,by=0.1) > a [1] 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 > a[1] == 0.1 [1] TRUE > a[2] == 0.2 [1] TRUE > a[3] == 0.3 [1] FALSE It turns out that the alternative > a = (1:9)/10 works just fine. Are there any good guides out there on how to deal

Hi, there, I cannot get accurate value for calculation. for example: ld<-sqrt(1*0.05*0.95*0.05*0.95) 0.05*0.95-ld=-6.938894e-18 0.05*0.95-ld==0 is False. I met this problem in my program, how can I handle it. Thanks. xj.

Full_Name: jan hattendorf Version: 2.9.0 OS: XP Submission from: (NULL) (213.3.108.185) I get an incorrect result for (41/10-1/10)%%1 [1] 1 The error did not occur with other numbers than 41 (1, 11, 21, 31, 51, ...) test <- rep(NA, 1000) for(i in 1:1000){ test[i] <- i/10-1/10 } test[test%%1==0]

Do you heve any idea why I get after this instruction everywhere false? > seq (0, 1, by=0.1) == 0.3 [1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE But after different step it's ok: > seq(0, 1, by=0.1) == 0.4 [1] FALSE FALSE FALSE FALSE TRUE FALSE FALSE FALSE FALSE FALSE FALSE -- View this message in context:

Hi, I'm having trouble with the "which" or the "seq" function, I'm not sure. Here's an example : > lat=seq(1,2,by=0.1) > lat [1] 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 > which(lat==1) [1] 1 > which(lat==1.1) [1] 2 > which(lat==1.2) [1] 3 > which(lat==1.3) [1] 4 > which(lat==1.4) [1] 5 > which(lat==1.5) [1] 6 >

Dear colleagues Please could someone kindly explain the following inconsistencies I've discovered when performing logical calculations in R: 8.8 - 7.8 > 1 > TRUE 8.3 - 7.3 > 1 > TRUE Thank you, Emma Jane [[alternative HTML version deleted]]

Hi all, please see my code: > library(zoo) > a <- as.yearmon("March-2010", "%B-%Y") > b <- as.yearmon("May-2010", "%B-%Y") > > nn <- (b-a)*12 # number of months in between them > nn [1] 2 > as.integer(nn) [1] 1 What is the correct way to find the number of months between "a" and "b", still

Hi all, In checking my R codes, I encountered the following problem. Is there a way to fix this? I tried to specify options(digits=). I did not fix the problem. Thanks so much for your help! Hanna > cdf(pmass)[2,2]==pcum[2,2][1] FALSE> cdf(pmass)[2,2][1] 0.9999758> pcum[2,2][1] 0.9999758 [[alternative HTML version deleted]]

With floating point numbers I'm seeing 'cut' putting values in the wrong bands. An example below places 0.3 in (0.3,0.6] i.e. 0.3 > 0.3. > x = 1:5*.1 > x [1] 0.1 0.2 0.3 0.4 0.5 > cut(x, br=c(0,.3,.6)) [1] (0,0.3] (0,0.3] (0.3,0.6] (0.3,0.6] (0.3,0.6] Levels: (0,0.3] (0.3,0.6] I'm sure this is probably the same issue documented in the FAQ (7.31 Why doesn't R

Hello, here is the version of R that I use : > version _ platform i486-pc-linux-gnu arch i486 os linux-gnu system i486, linux-gnu status major 2 minor 3.1 year 2006 month 06 day 01 svn rev 38247 language R version.string Version 2.3.1 (2006-06-01) And here is one of the sequences of

> length(sample(25000, 25000*(1-.55))) [1] 11249 > 25000*(1-.55) [1] 11250 > length(sample(25000, 11250)) [1] 11250 > length(sample(25000, 25000*.45)) [1] 11250 So the question is, why do I get 11249 out of the first command and not 11250? I can't figure this one out. Thanks Cory [[alternative HTML version deleted]]

Try this: 0.7-0.3==0.4 (We get FALSE) 0.7-0.3<0.4 (We get TRUE) but 0.8-0.3==0.5 (TRUE) 0.8-0.3<0.5 (FALSE) Funny, he? There is a way around: round(0.7-0.3,1)==0.4 (TRUE) Obviously there is a problem with some combinations of decimal subtractions, that - we have the feeling - shouldt be solved. Best regards Sven & Wolfgang -- View this message in context:

Try this: 0.7-0.3==0.4 (We get FALSE) 0.7-0.3<0.4 (We get TRUE) but 0.8-0.3==0.5 (TRUE) 0.8-0.3<0.5 (FALSE) Funny, he? There is a way around: round(0.7-0.3,1)==0.4 (TRUE) Obviously there is a problem with some combinations of decimal subtractions, that - we have the feeling - shouldt be solved. Best regards Sven & Wolfgang -- View this message in context:

(I use R 2.9.1 with win XP) If I run this code: seq(-0.1,.9, by = .05)[seq(-0.1,.9, by = .05) <= 0.5] I get this output: [1] -0.10 -0.05 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 Why is 0.50 not in the results ? (It seems that it gives a slightly bigger number then 0.5 but I don't understand why it does that) Where as if I try: seq(-0.1,.9, by = .05)[seq(-0.1,.9, by = .05) <=

Hello dear r-help group I am turning for you for help with FAQ number 7.31: "Why doesn't R think these numbers are equal?" http://cran.r-project.org/doc/FAQ/R-FAQ.html#Why-doesn_0027t-R-think-these-numbers-are-equal_003f *My story* is this: I wish to run many lm predictions and need to have them run fast. Using predict.lm is relatively slow, so I tried having it run faster by

Hi, Check the FAQ 7.31 https://cran.rstudio.com/doc/FAQ/R-FAQ.html#Why-doesn_0027t-R-think-these-numbers-are-equal_003f And read the posting guide too... https://www.r-project.org/posting-guide.html HTH, Ivan -- Dr. Ivan Calandra TraCEr, Laboratory for Traceology and Controlled Experiments MONREPOS Archaeological Research Centre and Museum for Human Behavioural Evolution Schloss Monrepos 56567

Perhaps somebody could clarify for me if the following is a floating point matter or otherwise, and how am I to correct for it? > floor(100*.1) [1] 10 > 100*(1.0-.9) [1] 10 > floor(100*(1-0.9)) [1] 9 Thanks! Michael _______________________________________________________ Michael Folkes Salmon Stock Assessment Canadian Dept. of Fisheries & Oceans Pacific Biological Station