[R] colSums in C

[Thomas Lumley]

On Tue, 18 Dec 2001, David Brahm wrote:
>
> Is there a macro that is equivalent to (as fast as) isnan() when it exists?
> ISNAN is definitely slower.
>

You should be able to test for NA or NaN pretty efficiently with
    x!=x
This doesn't work on systems without IEEE754 arithmetic, but more
importantly some compilers don't realise that it's a real test and
optimise it away.


	-thomas

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