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A set of functions is provided to test for `NA`

, `Inf`

,
`-Inf`

and `NaN`

. These functions are accessed *via* macros:

ISNA( |

and *via* function `R_IsNaN`

which is true for `NaN`

but not
`NA`

.

Do use `R_FINITE`

rather than `isfinite`

or `finite`

; the
latter is often mendacious and `isfinite`

is only available on a
some platforms, on which `R_FINITE`

is a macro expanding to
`isfinite`

.

Currently in C code `ISNAN`

is a macro calling `isnan`

.
(Since this gives problems on some C++ systems, if the R headers is
called from C++ code a function call is used.)

You can check for `Inf`

or `-Inf`

by testing equality to
`R_PosInf`

or `R_NegInf`

, and set (but not test) an `NA`

as `NA_REAL`

.

All of the above apply to *double* variables only. For integer
variables there is a variable accessed by the macro `NA_INTEGER`

which can used to set or test for missingness.

This document was generated by *root* on *April, 26 2012* using *texi2html 1.76*.