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mecej4
Joined: 31 Oct 2006
Posts: 1896
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 Posted: Sun Jan 07, 2024 6:49 pm Post subject: FTN95 does not process ASSOCIATE construct correctly |
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Paul, I do not have much experience using ASSOCIATE, and my expectations regarding what the following test program should do may be unjustified.
| Code: | program cubesift
implicit none
integer, parameter :: IMAX = 4
integer :: year, i, bits
integer, parameter :: cubes(IMAX) = [ (i*i*i, i = 1, IMAX) ]
bits = 1
associate (bmask => btest(bits,[(i-1, i = 1, IMAX)]))
year = sum(cubes, mask = bmask)
print '(i5, 4x,4L2)',year,bmask
end associate
end program |
FTN95 gives the output
whereas other compilers give
The array "cubes" contains [1^3, 2^3, 3^3, 4^3]. The mask array "bmask" has only the first element set to .T., so "sum" should be applied to just [1^3], yielding 1.
The FTN95-compiled code appears to make "bmask" a scalar 'T', which then gets replicated three times in the expression sum(cubes, mask = bmask). As a result, "year" is evaluated as sum([1^3, 2^3, 3^3, 4^3]), i.e., 100. |
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PaulLaidler
Site Admin
Joined: 21 Feb 2005
Posts: 8011
Location: Salford, UK
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| Posted: Mon Jan 08, 2024 10:06 am Post subject: |
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mecej4
Thank you for the bug report. I have logged this for investigation. |
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PaulLaidler
Site Admin
Joined: 21 Feb 2005
Posts: 8011
Location: Salford, UK
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| Posted: Thu Feb 01, 2024 12:22 pm Post subject: |
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| This failure has now been fixed for the next release of FTN95. |
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mecej4
Joined: 31 Oct 2006
Posts: 1896
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| Posted: Thu Feb 01, 2024 1:57 pm Post subject: |
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Thanks.
Here is the program from which the bug reproducer of this thread was created, if you wish to verify that the fix works on it, too.
| Code: |
! Given a range of years between 1 and 13^3-1, list years that may be
! expressed as the sum of cubes of integers with no repetitions allowed/
! Pipe the output of the program through the system SORT utility
program cubem
implicit none
integer, parameter :: YLOW = 2020, YHIGH = 2030
integer, parameter :: IMAX = 12 ! smallest possible I s.t. (I+1)^3 > YHIGH
integer :: year, i, nk, bits
integer, parameter :: cubes(IMAX) = [ (i*i*i, i = 1, IMAX) ]
nk = 0
do bits = 1, ishft (1, IMAX)-1
associate (bmask => btest(bits,[(i-1, i = 1, IMAX)]))
year = sum(cubes, mask = bmask)
if (year < YLOW .or. year > YHIGH) cycle
nk = nk+1
print '(i6,4x,10i3)',year,pack([(i, i = 1, IMAX)], mask=bmask)
end associate
end do
print '(/,A,i4,A)','Found ',nk,' years that are sums of cubes'
end program |
The expected output:
| Code: | 2024 2 3 4 5 6 7 8 9
2025 1 2 3 4 5 6 7 8 9
2023 2 5 6 7 11
2024 1 2 5 6 7 11
Found 4 years that are sums of cubes |
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PaulLaidler
Site Admin
Joined: 21 Feb 2005
Posts: 8011
Location: Salford, UK
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| Posted: Thu Feb 01, 2024 2:37 pm Post subject: |
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mecej4
Thanks. That also works. |
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