How to pass an input array to another subroutine?

[junziyang]

subroutineA
.......
CALLBVPMS(FCNEQN,FCNJAC,FCNBC,NEQNS,TLEFT,TRIGHT,DTOL,BTOL,MAXIT,NINIT,TINIT,YINIT,LDYINI,NMAX,NFINAL,TFINAL,YFINAL,LDYFIN)

endsubroutineA


subroutineFCNEQN(NEQNS,T,Y,P,DYDT)
......
!common/yy/Y
!REALY(NEQNS)
CALLNEQBF(FCN,N,XGUESS,XSCALE,FSCALE,IPARAM,RPARAM,X,FVEC)
......
endsubroutineFCNEQN

subroutineFCN(N,X,F)
......
!Y will be used in this subroutine
endsubroutineFCN

The code in GREEN issue the following error:
error#6406:Conflictingattributesormultipledeclarationofname.
error#6756:ACOMMONblockdataobjectmustnotbeanautomaticobject.

My Question: How to pass Y to subroutine FCN?

Thanks!

[TimP]

Quoting - junziyang

subroutineA
.......
CALLBVPMS(FCNEQN,FCNJAC,FCNBC,NEQNS,TLEFT,TRIGHT,DTOL,BTOL,MAXIT,NINIT,TINIT,YINIT,LDYINI,NMAX,NFINAL,TFINAL,YFINAL,LDYFIN)

endsubroutineA


subroutineFCNEQN(NEQNS,T,Y,P,DYDT)
......
!common/yy/Y
!REALY(NEQNS)
CALLNEQBF(FCN,N,XGUESS,XSCALE,FSCALE,IPARAM,RPARAM,X,FVEC)
......
endsubroutineFCNEQN

subroutineFCN(N,X,F)
......
!Y will be used in this subroutine
endsubroutineFCN

The code in GREEN issue the following error:
error#6406:Conflictingattributesormultipledeclarationofname.
error#6756:ACOMMONblockdataobjectmustnotbeanautomaticobject.

My Question: How to pass Y to subroutine FCN?

Thanks!

Are you asking more than one question? You could include the COMMON block in the subroutine, or pass a dummy argument (preferably with appropriate IN, OUT, or INOUT). In simple cases, the standard prohibits conflicts where there would be ambiguity between a dummy argument value passed at an earlier stage of execution, and a COMMON block value which is always up to date. In more complicated cases, the standard won't protect you.

[anthonyrichards]

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[Jugoslav_Dujic]

Quoting - junziyang

subroutineFCNEQN(NEQNS,T,Y,P,DYDT)
......
!common/yy/Y
!REALY(NEQNS)
CALLNEQBF(FCN,N,XGUESS,XSCALE,FSCALE,IPARAM,RPARAM,X,FVEC)
......

endsubroutineFCNEQN

The code in GREEN issue the following error:
error#6406:Conflictingattributesormultipledeclarationofname.
error#6756:ACOMMONblockdataobjectmustnotbeanautomaticobject.

My Question: How to pass Y to subroutine FCN?

Thanks!

You can use COMMON to share Y among different unis. What you cannot do is size the arrays in common dynamically -- NEQNS is a variable, and you cannot use that. It has to be a literal constant or a PARAMETER.

Alternatively, and more flexibly, you can define Y within a MODULE and USE that module in both routines. In that case, Y can be declared ALLOCATABLE, and you can ALLOCATE it to a desired size before use.

Finally, if you can change the source of NEQBF, you can pass Y through. If I recall correctly, it's an IMSL routine, so it's not an option.

[junziyang]

Quoting - Jugoslav Dujic

You can use COMMON to share Y among different unis. What you cannot do is size the arrays in common dynamically -- NEQNS is a variable, and you cannot use that. It has to be a literal constant or a PARAMETER.

Alternatively, and more flexibly, you can define Y within a MODULE and USE that module in both routines. In that case, Y can be declared ALLOCATABLE, and you can ALLOCATE it to a desired size before use.

Finally, if you can change the source of NEQBF, you can pass Y through. If I recall correctly, it's an IMSL routine, so it's not an option.

Thank you.

Yes, BVPMS and NEQBFare IMSL routines. The problem is Y isnot difined by me but passed to FCNEQN by BVPMS and its value is changing on each entry. So I cant't put Y in a module.

The fortran code is ina MATLAB Fortran mex file. NEQNS is passedin from MATLAB. IF I define NEQNS a parameter, then I have to change its valuewhen the number of equations changed and remex the programm. It's inconvenient.

According to your advice "not size the array in common", I delete the code "REAL Y(NEQNS), I got the following error:

error #6412: A dummy argument name is invalid in this context.

I have also tried the following code:

COMMON /pptr/ pt

REAL, POINTER :: pt

pt=> Y

error #6796: The variable must have the TARGET attribute or be a subobject of an object with the TARGET attribute, or it must have the POINTER attribute.

[Jugoslav_Dujic · Accepted solution]

Quoting - junziyang

I have also tried the following code:

COMMON /pptr/ pt

REAL, POINTER :: pt

pt=> Y

error #6796: The variable must have the TARGET attribute or be a subobject of an object with the TARGET attribute, or it must have the POINTER attribute.

Since you can't define the storage of Y, using a pointer seems a way to go.

However, your syntax is wrong. You need something like:

[cpp]subroutine FCNEQN(NEQNS, ..., Y, ...)
real, target:: Y(NEQNS)

real, pointer:: pY(:)
common /pptr/ pY
...
pY => Y[/cpp]