[R-pkg-devel] testing for NaN in C++ code

Hello,


You probably want one of the following
ISNA? ? ? ? ?TRUE for R's NA only
ISNAN? ? ? TRUE for R's and IEEE's NaN
R_IsNaN? ?TRUE for IEEE'S NaN only

On Fri, Mar 5, 2021, 20:55 Ben Bolker <bbolker at gmail.com 
<mailto:bbolker at gmail.com>> wrote:

    I would like to test for NaN inside C++ code that lives inside a CRAN
    package.

    Following the StackOverflow question linked below, I was using

    #define isNAN(a)? (a!=a)

    which I *think* used to work, but at some point along the way it
    stopped
    working due to compiler/flag changes. I'm thinking of switching to

    #define isNAN(a) std::isnan(a)

    instead. Does anyone have first-hand knowledge of having tried this and
    know if it works across the range of platforms/standard compilation
    flags that CRAN/R users are likely to experience?? Any other
    suggestions?

     ? I know that I should follow the problem upstream and detect it where
    it happens (see the answer titled "nan prevention" on SO), but in the
    meantime it would be nice to be able to do this robustly across all the
    platforms it's likely to see.

     ? ?cheers
     ? ? ?Ben Bolker


    https://stackoverflow.com/questions/570669/checking-if-a-double-or-float-is-nan-in-c/42138465#42138465
    <https://stackoverflow.com/questions/570669/checking-if-a-double-or-float-is-nan-in-c/42138465#42138465>