
forums.silverfrost.com Welcome to the Silverfrost forums

View previous topic :: View next topic 
Author 
Message 
mecej4
Joined: 31 Oct 2006 Posts: 1680

Posted: Sun May 01, 2022 1:19 pm Post subject: False error reports for correct program 


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*i1)
rn2=rn(2*i)
arg=2.0*pi*rn1
x1=sin(arg)
x2=cos(arg)
x3=sqrt(2.0*log(rn2))
gaussian(2*i1)=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 


Back to top 


PaulLaidler Site Admin
Joined: 21 Feb 2005 Posts: 7260 Location: Salford, UK

Posted: Mon May 02, 2022 9:40 am Post subject: 


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. 

Back to top 


mecej4
Joined: 31 Oct 2006 Posts: 1680

Posted: Mon May 02, 2022 9:53 am Post subject: 


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". 

Back to top 


JohnCampbell
Joined: 16 Feb 2006 Posts: 2374 Location: Sydney

Posted: Mon May 02, 2022 9:54 am Post subject: 


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 ? 

Back to top 


mecej4
Joined: 31 Oct 2006 Posts: 1680

Posted: Mon May 02, 2022 11:01 am Post subject: 


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. 

Back to top 




You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum

Powered by phpBB © 2001, 2005 phpBB Group
