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mecej4
Joined: 31 Oct 2006
Posts: 1899
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 Posted: Sun May 01, 2022 1:19 pm Post subject: False error reports for correct program |
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The following program is quite simple and it should be possible to compile and run this program with no errors.
| Code: | program pgm
implicit none
real, dimension(:,:), allocatable :: ev
integer i, nsub, mi
nsub = 10
mi = 5
ev = reshape( gaussian(nsub*mi),(/mi,nsub/) )
print *,(ev(1,i),i=1,5)
contains
function gaussian(n)
! return an array of gaussian random variates with variance 1
integer :: n
real, dimension(n) :: gaussian
real, dimension(n) :: rn
real :: rn1,rn2,arg,x1,x2,x3
real, parameter :: pi=4.0d0*atan(1.0)
integer :: i
if(mod(n,2) /= 0)stop 'Gaussian: argument must be an even integer'
call random_number(rn)
do i=1,n/2
rn1=rn(2*i-1)
rn2=rn(2*i)
arg=2.0*pi*rn1
x1=sin(arg)
x2=cos(arg)
x3=sqrt(-2.0*log(rn2))
gaussian(2*i-1)=x1*x3
gaussian(2*i)=x2*x3
enddo
end function gaussian
end program |
With no options or with /debug, the program aborts with
| Code: | | Error: Nonconformant arrays |
With /64 /check, the program aborts with
| Code: | | Integer arithmetic overflow |
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PaulLaidler
Site Admin
Joined: 21 Feb 2005
Posts: 8217
Location: Salford, UK
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| Posted: Mon May 02, 2022 9:40 am Post subject: |
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mecej4
Thank you for the feedback on this false error report. This is another instance of "allocate on assignment" not working. At the moment an explicit allocate
| Code: | | allocate(ev(mi,nsub)) |
is required before the call to RESHAPE.
It is interesting that you class this as a "simple" program. My first impression is that a fix will be quite difficult. |
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mecej4
Joined: 31 Oct 2006
Posts: 1899
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| Posted: Mon May 02, 2022 9:53 am Post subject: |
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| Quote: | | It is interesting that you class this as a "simple" program. |
Sorry, I guessed that because the allocation size of the array is knowable at compile time the compiler's job could be "simple". |
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JohnCampbell
Joined: 16 Feb 2006
Posts: 2615
Location: Sydney
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| Posted: Mon May 02, 2022 9:54 am Post subject: |
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Does function gaussian require a RESULT statement for where the value of the function is an array?
I thought this was a requirement for Fortran 95 ? |
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mecej4
Joined: 31 Oct 2006
Posts: 1899
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| Posted: Mon May 02, 2022 11:01 am Post subject: |
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Indeed, Fortran 95 requires:
| Quote: | | If the function result is array valued or a pointer, this shall be specified by specifications of the name of the result variable within the function body |
Later version of Fortran allow a declaration type spec to be used as a prefix spec in the FUNCTION statement as an alternative to a RESULTS clause.
We are grateful that FTN95 supports many of these features, although they did not exist in Fortran 95. |
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PaulLaidler
Site Admin
Joined: 21 Feb 2005
Posts: 8217
Location: Salford, UK
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| Posted: Mon Aug 01, 2022 7:38 am Post subject: |
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| The missing functionality for RESHAPE has now been added for the next release of FTN95. |
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