Modules and allocating
in [Fortran]
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From: Allamarein on 26 Jun 2010 06:25 I'm getting experience with modules. Therefore I try to compile a trivial statistical module for educational purpose. SUM function should sum the elements of an input array. I would to not specify array size, but my function should detect that. I tried the following code: MODULE STATISTICS CONTAINS REAL FUNCTION SUM(X) IMPLICIT NONE INTEGER :: N REAL :: RES=0.0 REAL, INTENT(IN), DIMENSION(:), ALLOCATABLE :: X N = SIZE(X) ALLOCATE(X(1:N)) DO I = 1,N RES = RES+X(I) END DO DEALLOCATE(X) SUM = RES END FUNCTION SUM END MODULE STATISTICS Anyway I get some errors. I suppose my problems are in the allocatable variables. If a write a function where I declare array size X (e.g. SUM(X,N) with N the array size), my module works properly. But I don't want this... What should I change my previous code? Thank you in advance
From: dpb on 26 Jun 2010 08:53 Allamarein wrote: > I'm getting experience with modules. > Therefore I try to compile a trivial statistical module for > educational purpose. > SUM function should sum the elements of an input array. > I would to not specify array size, but my function should detect that. > I tried the following code: > > MODULE STATISTICS > > CONTAINS > > REAL FUNCTION SUM(X) > IMPLICIT NONE > INTEGER :: N > REAL :: RES=0.0 REAL, INTENT(IN) :: X(:) > > N = SIZE(X) > DO I = 1,N > RES = RES+X(I) > END DO > > SUM = RES > END FUNCTION SUM > > END MODULE STATISTICS > > Anyway I get some errors. I suppose my problems are in the allocatable > variables. Indeed. You don't want an allocatable array here, you want an assumed-shape array where the number of dimensions is specified by the number of colons in the dimension expression and the size is that of the passed argument. It requires an explicit interface (which you get w/ the module automagically)... --
From: Allamarein on 26 Jun 2010 09:07 On 26 Giu, 14:53, dpb <n...(a)non.net> wrote: > Allamarein wrote: > > I'm getting experience with modules. > > Therefore I try to compile a trivial statistical module for > > educational purpose. > > SUM function should sum the elements of an input array. > > I would to not specify array size, but my function should detect that. > > I tried the following code: > > > MODULE STATISTICS > > > CONTAINS > > > REAL FUNCTION SUM(X) > > IMPLICIT NONE > > INTEGER :: N > > REAL :: RES=0.0 > > REAL, INTENT(IN) :: X(:) > > > > > N = SIZE(X) > > DO I = 1,N > > RES = RES+X(I) > > END DO > > > SUM = RES > > END FUNCTION SUM > > > END MODULE STATISTICS > > > Anyway I get some errors. I suppose my problems are in the allocatable > > variables. > > Indeed. > > You don't want an allocatable array here, you want an assumed-shape > array where the number of dimensions is specified by the number of > colons in the dimension expression and the size is that of the passed > argument. It requires an explicit interface (which you get w/ the > module automagically)... > > -- I found something about 'assumed-shape' array, but I don't understand very well. Would you suggest how you'd modify my code? I don't know how I can use an 'explicit interface'. Thank for your support
From: dpb on 26 Jun 2010 09:15 Allamarein wrote: .... > I found something about 'assumed-shape' array, but I don't understand > very well. I'd suggest reading the language reference manual w/ the compiler or programmers' guide or buy/check out one of the Fortran reference books available. You'll need it anyway for more than just this... > Would you suggest how you'd modify my code? I did in previous post. Look at the lines I moved to left and are not quoted any longer as well as having removed references to allocatable arrays. > I don't know how I can use an 'explicit interface'. As I also said in the previous post, the use of the module automagically generates the explicit interface for you...if you don't follow that, see above about resources... --
From: dpb on 26 Jun 2010 09:42
dpb wrote: > Allamarein wrote: > ... > >> I found something about 'assumed-shape' array, but I don't understand >> very well. > > I'd suggest reading the language reference manual w/ the compiler or > programmers' guide or buy/check out one of the Fortran reference books > available. You'll need it anyway for more than just this... .... BTW, I see from another posting you're using the IVF compiler -- by comparison to the product of the current Intel team that I have, I'm quite sure the documentation that came w/ the compiler is quite thorough in having both document types outlined above -- the Guide that is more general on Fortran language features as well as the specific language syntax manual. Use them. As it seems you're new to Fortran, I can't emphasize enough the usefulness of a a good reference book (or two). There are a multitude of threads in clf, some within the last couple of weeks even on recommendations/discussion of strengths of various titles currently available. -- |