NA in C/C++
On Sun, 28 May 2000 cstrato at EUnet.at wrote:
Dear Dr. Dalgaard
Thank you, too, for your fast response.
I have checked the web-site you mentioned. There is a function:
int isnan(floating-type x)
for floating point numbers, which I could use.
For integers I will check Arith.h and Arithmetic.c
Unfortunately, we found isnan is not 100% reliable. R defines int R_IsNaNorNA(double); for that purpose, and makes sure it works on all the platforms. (Note that some platforms that have isnan are marked as non-IEEE by the configure process.) My memory is that the real mess came with finite() and Inf/-Inf (at least one compiler had Inf < 3 true), but we also had problems with isnan returning a value which differed from true (as in 1 == 1).
Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272860 (secr) Oxford OX1 3TG, UK Fax: +44 1865 272595 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._