d9/d07/dlaisnan_8f_source.html

00001       LOGICAL FUNCTION DLAISNAN( DIN1, DIN2 )
00002 *
00003 *  -- LAPACK auxiliary routine (version 3.2.2) --
00004 *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
00005 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
00006 *     June 2010
00007 *
00008 *     .. Scalar Arguments ..
00009       DOUBLE PRECISION   DIN1, DIN2
00010 *     ..
00011 *
00012 *  Purpose
00013 *  =======
00014 *
00015 *  This routine is not for general use.  It exists solely to avoid
00016 *  over-optimization in DISNAN.
00017 *
00018 *  DLAISNAN checks for NaNs by comparing its two arguments for
00019 *  inequality.  NaN is the only floating-point value where NaN != NaN
00020 *  returns .TRUE.  To check for NaNs, pass the same variable as both
00021 *  arguments.
00022 *
00023 *  A compiler must assume that the two arguments are
00024 *  not the same variable, and the test will not be optimized away.
00025 *  Interprocedural or whole-program optimization may delete this
00026 *  test.  The ISNAN functions will be replaced by the correct
00027 *  Fortran 03 intrinsic once the intrinsic is widely available.
00028 *
00029 *  Arguments
00030 *  =========
00031 *
00032 *  DIN1    (input) DOUBLE PRECISION
00033 *
00034 *  DIN2    (input) DOUBLE PRECISION
00035 *          Two numbers to compare for inequality.
00036 *
00037 *  =====================================================================
00038 *
00039 *  .. Executable Statements ..
00040       DLAISNAN = (DIN1.NE.DIN2)
00041       RETURN
00042       END