LAPACK  3.7.0
LAPACK: Linear Algebra PACKage
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logical function dlaisnan ( double precision  DIN1,
double precision  DIN2 
)

DLAISNAN tests input for NaN by comparing two arguments for inequality.

Download DLAISNAN + dependencies [TGZ] [ZIP] [TXT]

Purpose:
 This routine is not for general use.  It exists solely to avoid
 over-optimization in DISNAN.

 DLAISNAN checks for NaNs by comparing its two arguments for
 inequality.  NaN is the only floating-point value where NaN != NaN
 returns .TRUE.  To check for NaNs, pass the same variable as both
 arguments.

 A compiler must assume that the two arguments are
 not the same variable, and the test will not be optimized away.
 Interprocedural or whole-program optimization may delete this
 test.  The ISNAN functions will be replaced by the correct
 Fortran 03 intrinsic once the intrinsic is widely available.
Parameters
[in]DIN1
          DIN1 is DOUBLE PRECISION
[in]DIN2
          DIN2 is DOUBLE PRECISION
          Two numbers to compare for inequality.
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date
December 2016