!>
!> IEEECK is called from the ILAENV to verify that Infinity and
!> possibly NaN arithmetic is safe (i.e. will not trap).
!> 

ISPEC

!>          ISPEC is INTEGER
!>          Specifies whether to test just for infinity arithmetic
!>          or whether to test for infinity and NaN arithmetic.
!>          = 0: Verify infinity arithmetic only.
!>          = 1: Verify infinity and NaN arithmetic.
!> 

ZERO

!>          ZERO is REAL
!>          Must contain the value 0.0
!>          This is passed to prevent the compiler from optimizing
!>          away this code.
!> 

ONE

!>          ONE is REAL
!>          Must contain the value 1.0
!>          This is passed to prevent the compiler from optimizing
!>          away this code.
!>
!>  RETURN VALUE:  INTEGER
!>          = 0:  Arithmetic failed to produce the correct answers
!>          = 1:  Arithmetic produced the correct answers
!> 

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