DLAISNAN(3)                MathKeisan LAPACK routine               DLAISNAN(3)



NAME
       DLAISNAN - i not for general use

SYNOPSIS
       LOGICAL FUNCTION DLAISNAN(DIN1,DIN2)

           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  argu-
       ments.  So  a  compiler  must assume that the two arguments are not the
       same variable, and the test will not be optimized away.   Interprocedu-
       ral  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.



 LAPACK auxiliary routine (versionNo3v.e1m)ber 2006                     DLAISNAN(3)