numeric-linalg

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*> \brief \b DLAISNAN tests input for NaN by comparing two arguments for inequality.
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DLAISNAN + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlaisnan.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlaisnan.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlaisnan.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       LOGICAL FUNCTION DLAISNAN( DIN1, DIN2 )
*
*       .. Scalar Arguments ..
*       DOUBLE PRECISION, INTENT(IN) :: DIN1, DIN2
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> 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.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] DIN1
*> \verbatim
*>          DIN1 is DOUBLE PRECISION
*> \endverbatim
*>
*> \param[in] DIN2
*> \verbatim
*>          DIN2 is DOUBLE PRECISION
*>          Two numbers to compare for inequality.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \ingroup laisnan
*
*  =====================================================================
      LOGICAL FUNCTION DLAISNAN( DIN1, DIN2 )
*
*  -- LAPACK auxiliary routine --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*
*     .. Scalar Arguments ..
      DOUBLE PRECISION, INTENT(IN) :: DIN1, DIN2
*     ..
*
*  =====================================================================
*
*  .. Executable Statements ..
      DLAISNAN = (DIN1.NE.DIN2)
      RETURN
      END