1*> \brief \b DLAISNAN tests input for NaN by comparing two arguments for inequality.
2*
3*  =========== DOCUMENTATION ===========
4*
5* Online html documentation available at
6*            http://www.netlib.org/lapack/explore-html/
7*
8*> \htmlonly
9*> Download DLAISNAN + dependencies
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11*> [TGZ]</a>
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13*> [ZIP]</a>
14*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlaisnan.f">
15*> [TXT]</a>
16*> \endhtmlonly
17*
18*  Definition:
19*  ===========
20*
21*       LOGICAL FUNCTION DLAISNAN( DIN1, DIN2 )
22*
23*       .. Scalar Arguments ..
24*       DOUBLE PRECISION, INTENT(IN) :: DIN1, DIN2
25*       ..
26*
27*
28*> \par Purpose:
29*  =============
30*>
31*> \verbatim
32*>
33*> This routine is not for general use.  It exists solely to avoid
34*> over-optimization in DISNAN.
35*>
36*> DLAISNAN checks for NaNs by comparing its two arguments for
37*> inequality.  NaN is the only floating-point value where NaN != NaN
38*> returns .TRUE.  To check for NaNs, pass the same variable as both
39*> arguments.
40*>
41*> A compiler must assume that the two arguments are
42*> not the same variable, and the test will not be optimized away.
43*> Interprocedural or whole-program optimization may delete this
44*> test.  The ISNAN functions will be replaced by the correct
45*> Fortran 03 intrinsic once the intrinsic is widely available.
46*> \endverbatim
47*
48*  Arguments:
49*  ==========
50*
51*> \param[in] DIN1
52*> \verbatim
53*>          DIN1 is DOUBLE PRECISION
54*> \endverbatim
55*>
56*> \param[in] DIN2
57*> \verbatim
58*>          DIN2 is DOUBLE PRECISION
59*>          Two numbers to compare for inequality.
60*> \endverbatim
61*
62*  Authors:
63*  ========
64*
65*> \author Univ. of Tennessee
66*> \author Univ. of California Berkeley
67*> \author Univ. of Colorado Denver
68*> \author NAG Ltd.
69*
70*> \ingroup OTHERauxiliary
71*
72*  =====================================================================
73      LOGICAL FUNCTION DLAISNAN( DIN1, DIN2 )
74*
75*  -- LAPACK auxiliary routine --
76*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
77*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
78*
79*     .. Scalar Arguments ..
80      DOUBLE PRECISION, INTENT(IN) :: DIN1, DIN2
81*     ..
82*
83*  =====================================================================
84*
85*  .. Executable Statements ..
86      DLAISNAN = (DIN1.NE.DIN2)
87      RETURN
88      END
89