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program main
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use, intrinsic :: iso_fortran_env, only : error_unit, sp=>real32, dp=>real64
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implicit none
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real(sp) :: a32
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real(dp) :: a64
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real(sp), parameter :: pi32 = 4*atan(1._sp)
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real(dp), parameter :: pi64 = 4*atan(1._dp)
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if (pi32 == pi64) error stop 'real32 values generally do not exactly equal real64 values'
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call timestwo(a32)
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call timestwo(a64)
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contains
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elemental subroutine timestwo(a)
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class(*), intent(inout) :: a
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select type (a)
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type is (real(sp))
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a = 2*a
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type is (real(dp))
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a = 2*a
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type is (integer)
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a = 2*a
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class default
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error stop 'requires real32, real64 or integer'
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end select
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end subroutine timestwo
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end program
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