C***********************************************************************
C
C                        naninfchk.f
C
C  	*****************************************************************
C 	* 								*
C	* 	Absoft Corporation 					* 
C 	*	2781 Bond Street					*
C	*	Rochester Hills, MI  48309				*
C	*								*
C	*	This file contains example code for demonstration	*
C	*	purposes only.  Absoft makes no warranty of the		* 
C	*	suitability of this code for any purpose.		*
C	*								*
C	*	In no event shall Absoft be liable for any incidental,	*
C	*	indirect, special, or consequential damages arising	*
C	*	out of the use of this code.				*
C	*								*
C	***************************************************************** 
C
C Routines to test real and double values against NaN and INF
C
C            NANCHK(X) - tests REAL*4 value X against NaN
C            DNANCHK(X) - tests REAL*8 value X against NaN
C            INFCHK(X) - tests REAL*4 value X against INF
C            DINFCHK(X) - test REAL*8 value X against INF
C
C For little endian machines (Intel x86), compile with
C
C      f77 -c -DBYTE_SWAPPED=1 naninfchk.f
C	or
C      f90 -c -DBYTE_SWAPPED=1 naninfchk.f -YBOZTYPE=INT
C
C For big endian machines (PowerPC), compile with
C
C      f77 -c naninfchk.f
C	or
C      f90 -c naninfchk.f -YBOZTYPE=INT
C
C***********************************************************************

        LOGICAL FUNCTION NANCHK(X)
        IMPLICIT NONE
        REAL X,Y
        INTEGER I
        EQUIVALENCE(Y,I)
        Y = X
        NANCHK = ((I .AND. z'7f80 0000') .EQ. z'7f80 0000') .AND.
     +           ((I .AND. z'007f ffff') .NE. z'0000 0000')
        RETURN
        END

        LOGICAL FUNCTION DNANCHK(X)
        IMPLICIT NONE
        REAL*8 X,Y
        INTEGER I(2)
        EQUIVALENCE(Y,I)
        Y = X
$IF (DEFINED(BYTE_SWAPPED))
        DNANCHK = ((I(2) .AND. z'7ff0 0000') .EQ. z'7ff0 0000') .AND.
     +           (((I(2) .AND. z'000f ffff') .NE. z'0000 0000') .OR.
     +             (I(1) .NE. 0))
$ELSE
        DNANCHK = ((I(1) .AND. z'7ff0 0000') .EQ. z'7ff0 0000') .AND.
     +           (((I(1) .AND. z'000f ffff') .NE. z'0000 0000') .OR.
     +             (I(2) .NE. 0))
$ENDIF
        RETURN
        END

        LOGICAL FUNCTION INFCHK(X)
        IMPLICIT NONE
        REAL X,Y
        INTEGER I
        EQUIVALENCE(Y,I)
        Y = X
        INFCHK = ((I .AND. z'7f80 0000') .EQ. z'7f80 0000') .AND.
     +           ((I .AND. z'007f ffff') .EQ. z'0000 0000')
        RETURN
        END

        LOGICAL FUNCTION DINFCHK(X)
        IMPLICIT NONE
        REAL*8 X,Y
        INTEGER I(2)
        EQUIVALENCE(Y,I)
        Y = X
$IF (DEFINED(BYTE_SWAPPED))
        DINFCHK = ((I(2) .AND. z'7ff0 0000') .EQ. z'7ff0 0000') .AND.
     +           (((I(2) .AND. z'000f ffff') .EQ. z'0000 0000') .AND.
     +             (I(1) .EQ. 0))
$ELSE
        DINFCHK = ((I(1) .AND. z'7ff0 0000') .EQ. z'7ff0 0000') .AND.
     +           (((I(1) .AND. z'000f ffff') .EQ. z'0000 0000') .AND.
     +             (I(2) .EQ. 0))
$ENDIF
        RETURN
        END