On 8/31/07, Duncan Murdoch <[EMAIL PROTECTED]> wrote: > The IEEE floating point standard allows for negative zero, but it's hard > to know that you have one in R. One reliable test is to take the > reciprocal. For example, > > > y <- 0 > > 1/y > [1] Inf > > y <- -y > > 1/y > [1] -Inf > > The other day I came across one in complex numbers, and it took me a > while to figure out that negative zero was what was happening: > > > x <- complex(real = -1) > > x > [1] -1+0i > > 1/x > [1] -1+0i > > x^(1/3) > [1] 0.5+0.8660254i > > (1/x)^(1/3) > [1] 0.5-0.8660254i > > (The imaginary part of 1/x is negative zero.) > > As a Friday question: are there other ways to create and detect > negative zero in R?
I think the only other way is the IEEE CopySign function but I don't think R has implemented it -- R probably should. Google CopySign . ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel