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+      LOGICAL FUNCTION DLAISNAN(DIN1,DIN2)
+*
+*  -- LAPACK auxiliary routine (version 3.1) --
+*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
+*     November 2006
+*
+*     .. Scalar Arguments ..
+      DOUBLE PRECISION DIN1,DIN2
+*     ..
+*
+*  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.
+*
+*  Strictly speaking, Fortran does not allow aliasing of function
+*  arguments. So 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.
+*
+*  Arguments
+*  =========
+*
+*  DIN1     (input) DOUBLE PRECISION
+*  DIN2     (input) DOUBLE PRECISION
+*          Two numbers to compare for inequality.
+*
+*  =====================================================================
+*
+*  .. Executable Statements ..
+      DLAISNAN = (DIN1.NE.DIN2)
+      RETURN
+      END