I have been told by the CRAN administrators that the following code generated an error on 64-bit Fedora Linux (gcc, clang) and on Solaris machines (sparc, x86), but runs well on all other systems):
> fn <- function(x, y) ifelse(x^2 + y^2 <= 1, 1 - x^2 - y^2, 0) > tol <- 1.5e-8 > fy <- function(x) integrate(function(y) fn(x, y), 0, 1, subdivisions = 300, rel.tol = tol)$value > Fy <- Vectorize(fy) > xa <- -1; xb <- 1 > Q <- integrate(Fy, xa, xb, subdivisions = 300, rel.tol = tol)$value Error in integrate(Fy, xa, xb, subdivisions = 300, rel.tol = tol) : roundoff error was detected Obviously, this realizes a double integration, split up into two 1-dimensional integrations, and the result shall be pi/4. I wonder what a 'roundoff error' means in this situation. In my package, this test worked well, w/o error or warnings, since July 2011, on Windows, Max OS X, and Ubuntu Linux. I have no chance to test it on one of the above mentioned systems. Of course, I can simply disable these tests, but I would not like to do so w/o good reason. If there is a connection to a bug fix to integrate(), with NEWS item "integrate() reverts to the pre-2.12.0 behaviour. (PR#15219)", then I do not understand what this pre-2.12.0 behavior really means. Thanks for any help or a hint to what shall be changed. Hans W Borchers PS: This kind of tricky definition in function 'fn' has caused some discussion on this list in July 2009. I still think it should be allowed to proceed in this way. ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel