[Rd] hashing NaN (PR#1267)

tlumley@u.washington.edu tlumley@u.washington.edu
Thu, 17 Jan 2002 01:30:08 +0100 (MET)

Different NaNs can hash to different values and so be treated differently
by duplicated(), unique(), match(). Any IEEE double value with exponent
bits all 1 is NaN (except the one that is NA).

AFAICT all arithmetic and mathematical operations in R produce the same
NaN, but this is not guaranteed by any standard. read.spss() will produce
different NaNs when reading missing values in at least some circumstances.


Thomas Lumley			Asst. Professor, Biostatistics
tlumley@u.washington.edu	University of Washington, Seattle

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