Feature/complete pr799

[eddelbuettel]

No description provided.

[krlmlr]

I'd prefer std::isnan() because it's faster by another x1.5, but this also comes with a slight risk. What do you think?

[eddelbuettel]

Let's review this in the next cycle. I have much more profound problems with this 0.12.15 candidate now.

[eddelbuettel]

Also, R has NA and NaN, the standard only has the latter so I prefer R in general for this.

[krlmlr]

R's NA is a special NaN, always has been, and probably will be forever. But I agree it's safer to use R_cppisnan().

[kevinushey]

R-exts has this to say about std::isnan():

Functions/macros such as isnan, isinf and isfinite are not required by C++98: where compilers support them they may be only in the std namespace or only in the main namespace. There is no way to make use of these functions which works with all C++ compilers currently in use on R platforms: use R’s versions such as ISNAN and R_FINITE instead.

which is a long-winded way of saying, "if you use std::isnan(), CRAN may yell at you later when it breaks on Solaris". So if we did switch to std::isnan() we should guard that usage based on whether gcc / clang is being used as the compiler.

[krlmlr]

Thanks. I missed the "C++11" requirement for std::isnan(): http://en.cppreference.com/w/c/numeric/math/isnan. Let's stick with the API.