Hi [EMAIL PROTECTED] napsal dne 03.03.2008 20:12:34:
> Thanks for all response. Here is more closer to my question, > p<-0.05 > > f<-0.05 > > ld<-sqrt(f* (1 - f) * p * (1 - p)) > > D <- (p * (1 - f) - ld)/p > > d <- ((1 - p) * f - ld)/(1 - p) > > haplo<-data.frame(D,d) > > > haplo > D d > 1 -1.387779e-16 -7.304099e-18 > > cond1<-pmin(haplo[,1],haplo[,2]) > > haplo[cond1>=0,] Either do not use computers as they sometimes can not represent exactly fractional values. Or use rounding, haplo[round(cond1, 10)>=0,] Regards Petr > > But the program cannot get right one, because > > > -1.387779e-16>=0 is FALSE > > -7.304099e-18>=0 is FALSE > > > > Thank you! > > xj. > > > ----- Original Message ----- > From: "Gavin Simpson" <[EMAIL PROTECTED]> > To: "Xuejun Qin" <[EMAIL PROTECTED]> > Cc: <r-help@r-project.org> > Sent: Monday, March 03, 2008 12:57 PM > Subject: Re: [R] help for the first poster- a simple question > > > > On Mon, 2008-03-03 at 12:52 -0500, Xuejun Qin wrote: > >> Hi, there, > >> I cannot get accurate value for calculation. > >> for example: > >> ld<- > >> 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. > > > > Answer 1: > > > > Read FAQ 7.31 - > > > > http://cran.r-project.org/doc/FAQ/R-FAQ.html#Why-doesn_0027t-R-think-these- > numbers-are-equal_003f > > > > Answer 2: > > > > Use all.equal() > > > >> ld<-sqrt(1*0.05*0.95*0.05*0.95) > >> 0.05*0.95-ld > > [1] -6.938894e-18 > >> 0.05*0.95-ld==0 > > [1] FALSE > >> all.equal(0.05*0.95-ld, 0) > > [1] TRUE > > > >> > >> > >> xj. > > > > HTH > > > > G > > -- > > %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% > > Dr. Gavin Simpson [t] +44 (0)20 7679 0522 > > ECRC, UCL Geography, [f] +44 (0)20 7679 0565 > > Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk > > Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/ > > UK. WC1E 6BT. [w] http://www.freshwaters.org.uk > > %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% > > > > > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
