On Mon, Jul 21, 2008 at 4:15 PM, Andries E. Brouwer <Andries.Brouwer@xxxxxx> wrote: > On Mon, Jul 21, 2008 at 01:36:52PM +0200, Michael Kerrisk wrote: >> Hi Andries, >> >> Reading the POSIX.1 specs of various functions, I see that sometimes >> they talk of the return value of a function as being +0, sometimes >> +-0, and sometimes -0. Does one need to care about this? > > Yes. > > These are different floating point values, and sometimes the > difference is important. In cases of total loss of precision > it is the only bit left. At a branch cut one has a discontinuity > and for example the imaginary part of clog(0.0) will be 0 > while the imaginary part of clog(-0.0) is pi*I. Thanks Andries. I will attend to the difference in my updates. Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ man-pages online: http://www.kernel.org/doc/man-pages/online_pages.html Found a bug? http://www.kernel.org/doc/man-pages/reporting_bugs.html -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
