Matt Zimmerman wrote: > > Mathematically speaking, 1.0/0.0 is undefined while 0.0/0.0 is indeterminate, > and those do not mean the same thing. From a programming standards > perspective, as far as I know, IEEE 754 says that there are multiple > permissible representations for NaN and infinity (not all bits are defined). > So there are values for which, within rrdtool: > > isnan(x) && x != DNAN > and > isinf(x) && x != DINF
Good to know. > I would hope that rrdtool only uses these macros to obtain reasonable values > to > use in its internal storage format, and not for any comparisons (where the > IEEE > functions should be used). A quick scan doesn't reveal any such comparisons. I'll check more careful later on. > As long as this is true, the expressions for DNAN and DINF are a perfectly > valid way to obtain some values which will satisfy finite/isnan/isinf in the > expected ways: IEEE defines that isnan(0.0/0.0) and isinf(1.0/0.0) will both > be true. Do you also happen to know the official way to handle isnan(1.0/0.0) ? > I missed the original post...is there some compiler which is not handling > these > expressions correctly? It was about porting to VB OCX or something alike. I don't know if it was asked because it fails in VB or not. cheers, -- __________________________________________________________________ / [EMAIL PROTECTED] [EMAIL PROTECTED] \ | work private | | My employer is capable of speaking therefore I speak only for myself | +----------------------------------------------------------------------+ | Technical questions sent directly to me will be nuked. Use the list. | +----------------------------------------------------------------------+ | http://faq.mrtg.org/ | | http://rrdtool.eu.org --> tutorial | +----------------------------------------------------------------------+ -- Unsubscribe mailto:[EMAIL PROTECTED] Help mailto:[EMAIL PROTECTED] Archive http://www.ee.ethz.ch/~slist/rrd-developers WebAdmin http://www.ee.ethz.ch/~slist/lsg2.cgi
