similar to: Modular Arithmetic Error?

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]

> > as.numeric(ImpVol[1,5,57]) == 0.0001 [1] FALSE > > as.numeric(ImpVol[1,5,57]) [1] 1e-04 > > 0.0001 [1] 1e-04 > Any tips? Thanks Sean R 2.15.3 windows 7

Hi Everyone, as part of a larger script, I need to insert the result of a simple minus operation into an if statement. I have noticed that the precision that appear on the screen is not the precision in which R stores the result of the minus operation, and that this change alters the result of the if statement. For example, when running this simple script:   > a=0.90 > b=0.95 >

Hi everybody, given a fresh rgui.exe load on winxp OS, I enter (a minimal exaple) n <- 12.357531 Then the following command: n <- (n - floor(n))*10; n gives the following outputs: [1] 3.57531 [1] 5.7531 [1] 7.531 [1] 5.31 [1] 3.1 [1] 1 === still as expected [1] 10 === not expected, count with me: 1 - floor(1) is zero, times 10 gives 0, not 10!!!! [1] 10 === should

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

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.

Why, in R, does (0.1 + 0.05) > 0.15 evaluate to True? What am I missing here? How can I ensure this (ostensibly incorrect) behavior doesn't introduce bugs into my code? Thanks for your time. Dave Mitchell [[alternative HTML version deleted]]

To the R development team: First of all, thank you so much for maintaining wonderful R software. Perhaps, Dr. Ahn has just reported an error on the wilcox.test() function, and suggesting that an error may arise from abs() and rank(). I just had a quick check that the problem may come from the precision of the results of arithmetic functions. 87.7-89.1+1.4 # > 87.7-89.1+1.4 # [1]

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, 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]]

> 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]]

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

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:

Full_Name: Paul Eckermann Version: 2.7.1 OS: Windows XP Service Pack 2 Submission from: (NULL) (129.127.183.12) This is the first time I have submitted a bug report, so apologies if I have not followed the correct protocol. If I enter length(rnorm(100*.29)) it returns 28 rather than 29. y<-(1:100)/100 z<-sapply(y,function(x) length(rnorm(x*100))) z!=100*y indicates that it has

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, My personal opinion: Just to be sure I understand what you're considering: you want to write a backend that will produce optimized machine code for a device with modular arithmetic instructions (not simulate such a device on a standard CPU)? In which case, won't the same assumptions that are embodied in the transformations for the case of unsigned 2's complement arithmetic (in

I've been playing around with LLVM to write a backend for a rather "simple" (co-)processor. Assume that only three arithmetic instructions exist: ADD mod N, SUB mod N and MUL mod N. The modulus N is programmable and stored in a register. No ordinary arithmetic instructions are available. The word size is 256-bit. In other words, the following function, b + c mod N, corresponds to

Hi, I know there's been some talk about bignums already, this is similar to it, but not exactly the same. I'm currently using LLVM for my master thesis. The goal is to make a compiler for zero-knowledge proofs of knowledge protocols. This compiler should target embedded devices. There's a language called the protocol implementation language in which these protocols should be

Thanks for your insightful suggestions. Yes, I am programming for a real device that does modular arithmetic (and only modular arithmetic). The modulus N is fixed during a single launch of a program. One way I could also come up with is to simply use add i256 %a, %b to represent a + b mod n, and let LLVM passes to reason about possible optimizations. However these are not semantically identical