program main

    complex(8),allocatable::array(:,:)

    allocate(array(17, 17))
    array = 1.0d0

    call fft(array(1:16,1:16))

contains

    subroutine fft(a)
        use mkl_dfti

        implicit none

        complex(8),intent(inout)::a(:,:)

        type(dfti_descriptor),pointer::desc
        integer::stat

        stat = DftiCreateDescriptor(desc, DFTI_DOUBLE, DFTI_COMPLEX, 2, shape(a) )
        stat = DftiCommitDescriptor(desc)
        stat = DftiComputeForward(desc, a(:,1))
        stat = DftiFreeDescriptor(desc)

    end subroutine

end program

program main
    implicit none

    real(8),allocatable::a(:,:)

    pause

    allocate(a(8192,8192))

    pause

    call random_number(a)

    pause

    call foo(a(:4096,:4096))

    pause

    contains

    subroutine foo(a)
        implicit none

        real(8)::a(:,:)

        open(unit=16, file='a_sum.txt')

        write(16, *) sum(a)

        close(16)

    end subroutine

end program

module m_foo
    implicit none

contains

    subroutine foo(a)
        implicit none

        real(8),contiguous::a(:,:)

        integer::i, j

        open(unit=16, file='a_sum.txt')

        write(16, *) sum(a)

        close(16)

        call nointerface(a)

    end subroutine

end module

subroutine nointerface(a)
    implicit none

    real(8)::a(*)

end subroutine

program main
    use m_foo

    implicit none

    integer,parameter::N = 8192
    real(8),allocatable::a(:,:)

    integer::i, j
    real(8)::count

    pause

    allocate(a(N, N))

    pause

    call random_number(a)

    pause

    call foo(a(:N/2,:N/2))

    pause

end program

program main
    implicit none

    complex(8),allocatable::a(:,:)

    allocate(a(16,16))

    a = 0.0d0
    a(1:4,1:4) = 1.0d0

    call fft(a(1:4,1:4))

    write(*,*) a(1:4,1:4)

    pause

    a = 0.0d0
    a(1:4,1:4) = 1.0d0

    call fft_stride(a(1:4,1:4), 1, 16)

    write(*,*) a(1:4,1:4)

    pause

    contains

    subroutine fft(a)  !{{{
        use mkl_dfti

        implicit none

        complex(8),intent(inout)::a(:,:)

        type(dfti_descriptor),pointer::desc
        integer::stat

        stat = DftiCreateDescriptor(desc, DFTI_DOUBLE, DFTI_COMPLEX, 2, shape(a) )
        stat = DftiCommitDescriptor(desc)
        stat = DftiComputeForward(desc, a(:,1))
        stat = DftiFreeDescriptor(desc)

    end subroutine  !}}}

    subroutine fft_stride(a, s1, s2)  !{{{
        use mkl_dfti

        implicit none


        complex(8),intent(inout)::a(:,:)
        integer::s1, s2

        type(dfti_descriptor),pointer::desc
        integer::stat

        integer::strides(3)

        strides = [0, s1, s2]

        stat = DftiCreateDescriptor(desc, DFTI_DOUBLE, DFTI_COMPLEX, 2, shape(a) )
        stat = DftiSetValue(desc, DFTI_INPUT_STRIDES, strides)
        stat = DftiCommitDescriptor(desc)
        stat = DftiComputeForward(desc, a(:,1))
        stat = DftiFreeDescriptor(desc)

    end subroutine  !}}}

end program

program ...
call fft(4,4,a(1:4,1:4))
end program

subroutine fft(m,n,a)  !{{{
use mkl_dfti

implicit none

complex(8),intent(inout)::a(*)
integer :: m, n

type(dfti_descriptor),pointer::desc
integer::stat

stat = DftiCreateDescriptor(desc, DFTI_DOUBLE, DFTI_COMPLEX, 2, (/m,n/) )
stat = DftiCommitDescriptor(desc)
stat = DftiComputeForward(desc, a)
stat = DftiFreeDescriptor(desc)

end subroutine !}}}

program ...
call fft_strided(4,4,a,16)
end program

subroutine fft_strided(m,n,a,lda)  !{{{
use mkl_dfti

implicit none

complex(8),intent(inout)::a(*)
integer :: m, n, lda

type(dfti_descriptor),pointer::desc
integer::stat

integer::strides(3)

strides = [0, 1, lda]

stat = DftiCreateDescriptor(desc, DFTI_DOUBLE, DFTI_COMPLEX, 2, (/m,n/) )
stat = DftiSetValue(desc, DFTI_INPUT_STRIDES, strides)
stat = DftiCommitDescriptor(desc)
stat = DftiComputeForward(desc, a)
stat = DftiFreeDescriptor(desc)

end subroutine !}}}

integer, dimension(10:20) :: array
integer :: i

array = [ (i, i=10,20) ]
call foo(array(10:20:2))

subroutine foo(a)
    integer, dimension(:) :: a
    integer :: i

    print*, lbound(a), ubound(a)
    do i=lbound(a,1), ubound(a,2)
        print*, a(i)
    end do

end subroutine foo

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integer, dimension(10:) :: a