Clarify An Old Question: define a user data containing array with dimensions decided in running time
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From: Hifi-Comp on 18 May 2010 21:51 My original question was not clear and get sidetracked. Hence I am trying to clarify the question: Currently I have the following: INTEGER,PARAMETER:: n=3 TYPE,PUBLIC:: User_Data REAL(DBL_AD)::scale REAL(DBL_AD)::vector(n) END TYPE User_Data TYPE(User_Data):: x, y(30),z(100,10) In the real situation, I want the user of compiled code to input n (remain the same throughout the calculation) and with almost no changes to the original code. Richard suggested to change the type definition as follows TYPE,PUBLIC:: User_Data REAL(DBL_AD)::scale REAL(DBL_AD),ALLOCATABLE::vector(:) END TYPE User_Data However, I don't want to insert allocate statement for each variables of User_Data as there are many such types in the overall program. It seems to me I should be able to do something like ALLOCATE(USER_DATA%VECTOR(N)) to fix the dimension of vector, and all the variables of User_Data will then know the dimension already. Is it posslbe to achieve this?
From: steve on 18 May 2010 21:56 On May 18, 6:51 pm, Hifi-Comp <wenbinyu.hea...(a)gmail.com> wrote: > My original question was not clear and get sidetracked. Hence I am > trying to clarify the question: > > Currently I have the following: > > INTEGER,PARAMETER:: n=3 > > TYPE,PUBLIC:: User_Data > REAL(DBL_AD)::scale > REAL(DBL_AD)::vector(n) > END TYPE User_Data > > TYPE(User_Data):: x, y(30),z(100,10) > > In the real situation, I want the user of compiled code to input n > (remain the same throughout the calculation) and with almost no > changes to the original code. > > Richard suggested to change the type definition as follows > TYPE,PUBLIC:: User_Data > REAL(DBL_AD)::scale > REAL(DBL_AD),ALLOCATABLE::vector(:) > END TYPE User_Data > > However, I don't want to insert allocate statement for each variables > of User_Data as there are many such types in the overall program. It > seems to me I should be able to do something like > > ALLOCATE(USER_DATA%VECTOR(N)) > > to fix the dimension of vector, and all the variables of User_Data > will then know the dimension already. Is it posslbe to achieve this? No. See Richard's previous response. PS: You can't ALLOCATE something that does not have the ALLOCATABLE (or POINTER) attribute. -- steve
From: Hifi-Comp on 18 May 2010 22:10 So you are saying there is no way in Fortran to accomplish what I intended to do: changing the original global constant n, which used to define the dimension of the array, into a user input one, with minimized change to the original code. On May 18, 9:56 pm, steve <kar...(a)comcast.net> wrote: > On May 18, 6:51 pm, Hifi-Comp <wenbinyu.hea...(a)gmail.com> wrote: > > > > > > > My original question was not clear and get sidetracked. Hence I am > > trying to clarify the question: > > > Currently I have the following: > > > INTEGER,PARAMETER:: n=3 > > > TYPE,PUBLIC:: User_Data > > REAL(DBL_AD)::scale > > REAL(DBL_AD)::vector(n) > > END TYPE User_Data > > > TYPE(User_Data):: x, y(30),z(100,10) > > > In the real situation, I want the user of compiled code to input n > > (remain the same throughout the calculation) and with almost no > > changes to the original code. > > > Richard suggested to change the type definition as follows > > TYPE,PUBLIC:: User_Data > > REAL(DBL_AD)::scale > > REAL(DBL_AD),ALLOCATABLE::vector(:) > > END TYPE User_Data > > > However, I don't want to insert allocate statement for each variables > > of User_Data as there are many such types in the overall program. It > > seems to me I should be able to do something like > > > ALLOCATE(USER_DATA%VECTOR(N)) > > > to fix the dimension of vector, and all the variables of User_Data > > will then know the dimension already. Is it posslbe to achieve this? > > No. > > See Richard's previous response. > > PS: You can't ALLOCATE something that does not have the > ALLOCATABLE (or POINTER) attribute. > > -- > steve- Hide quoted text - > > - Show quoted text -
From: steve on 18 May 2010 22:43 On May 18, 7:10 pm, Hifi-Comp <wenbinyu.hea...(a)gmail.com> wrote: > So you are saying there is no way in Fortran to accomplish what I > intended to do: changing the original global constant n, which used to > define the dimension of the array, into a user input one, with > minimized change to the original code. > Well, your top posting has forced a loss of context, but yes that's what I'm (and others are) saying. Other than allowing free-form source code, dynamic memory management is perhaps the most important change to Fortran when Fortran 90 was ratified 2 decades ago. The only way that comes close to what you want is to massively over-commit static allocation, and then check that a user doesn't enter a value that exceeds the upper limit. INTEGER,PARAMETER:: upper_limit = 1024 TYPE,PUBLIC:: User_Data REAL(DBL_AD)::scale REAL(DBL_AD)::vector(upper_limit) END TYPE User_Data TYPE(User_Data):: x, y(30),z(100,10) read(*,*) n if (n > upper_limit) then stop 'Upper limit of static array allocation exceeded' end if -- steve
From: robin on 18 May 2010 23:12
"Hifi-Comp" <wenbinyu.heaven(a)gmail.com> wrote in message news:ab15b088-db79-4d5a-b07d-106d3c7e8e61(a)y12g2000vbg.googlegroups.com... >So you are saying there is no way in Fortran to accomplish what I >intended to do: changing the original global constant n, which used to >define the dimension of the array, into a user input one, with >minimized change to the original code. Have you investigated introducing a new main program in which the bound(s) of the array are read in, and which then passes that array to the original main program (suitably midified). Any subsequent reference to that array would need to have a declaration of the form real A(*) or real A(:). That may be adequate for a few arrays, but in general any change from static to dynamic in Fortran will involve significant changes. |