Hi
I need to pass a 2D array of ints to user defined functions, especially RHS.
Ideally, this 2D array is dynamically created at run time to make my
application general. Yesterday's discussion is below.
I did this in the application context:
/* User-defined data structures and routines */
/* AppCtx: used by FormIFunction() */
typedef struct {
DM da; // DM instance in which u, r are placed.
PetscInt geometry[usr_MY][usr_MX]; // This is static, so the whole thing is
visible to everybody who gets the context. This is my working solution as of
now.
Vec geom; // I duplicate u for this in calling function. VecDuplicate(
u , &user.geom). I cannot pass this to RHS function, I cannot access values in
geom in the called function.
PetscInt **geomet; // I calloc this in the calling function. I cannot access
the data in RHS function
int **anotherGeom; // just int.
} AppCtx;
This static geometry 2D array can be seen in all functions that receive the
application context. This is a working solution to my problem, although not
ideal. The ideal solution would be if I can pass and receive something like
geom or geomet which are dynamically created after the 2D DA is created in the
calling function.
I am working through the manual and the examples, but some indication of how to
solve this specific issue will be great.
cheers
Sanjay
________________________________
From: Matthew Knepley [[email protected]]
Sent: 04 February 2015 21:03
To: Sanjay Kharche
Cc: [email protected]
Subject: Re: [petsc-users] passing information to TSIFunction
On Wed, Feb 4, 2015 at 2:59 PM, Sanjay Kharche
<[email protected]<mailto:[email protected]>> wrote:
Hi
I started with the ex15.c example from ts. Now I would like to pass a 2D int
array I call data2d to the FormIFunction which constructs the udot - RHS.
FormIFunction is used in Petsc's TSSetIFunction. My data2d is determined at run
time in the initialisation on each rank. data2d is the same size as the
solution array and the residual array.
I tried adding a Vec to FormIFunction, but Petsc's TSIFunction (
TSSetIFunction(ts,r,FormIFunction,&user); ) expects a set number & type of
arguments to FormIFunction. I tried passing data2d as a regular int pointer as
well as a Vec. As a Vec, I tried to access the data2d in a similar way as the
solution vector, which caused the serial and parallel execution to produce
errors.
1) This is auxiliary data which must come in through the context argument. Many
many example use a context
2) You should read the chapter on DAs in the manual. It describes the data
layout. In order for your code to
work in parallel I suggest you use a Vec and cast to int when you need the
value.
Thanks,
Matt
Any ideas on how I can get an array of ints to FormIFunction?
thanks
Sanjay
The function declaration:
// petsc functions.
extern PetscInt FormIFunction(TS,PetscReal,Vec,Vec,Vec,void*, Vec); // last Vec
is supposed to be my data2D, which is a duplicate of the u.
I duplicate as follows:
DMDACreate2d(PETSC_COMM_WORLD, DM_BOUNDARY_NONE,
DM_BOUNDARY_NONE,DMDA_STENCIL_STAR,usr_MX,usr_MY,PETSC_DECIDE,PETSC_DECIDE,1,1,NULL,NULL,&da);
user.da = da;
DMCreateGlobalVector(da,&u);
VecDuplicate(u,&r);
VecDuplicate(u,&Data2D); // so my assumption is that data2D is part of da,
but I cannot see/set its type anywhere
The warnings/notes at build time:
> make sk2d
/home/sanjay/petsc/linux-gnu-c-debug/bin/mpicc -o sk2d.o -c -fPIC -Wall
-Wwrite-strings -Wno-strict-aliasing -Wno-unknown-pragmas -g3 -O0
-I/home/sanjay/petsc/include -I/home/sanjay/petsc/linux-gnu-c-debug/include
`pwd`/sk2d.c
/home/sanjay/petscProgs/Work/twod/sk2d.c: In function ‘main’:
/home/sanjay/petscProgs/Work/twod/sk2d.c:228:4: warning: passing argument 3 of
‘TSSetIFunction’ from incompatible pointer type [enabled by default]
/home/sanjay/petsc/include/petscts.h:261:29: note: expected ‘TSIFunction’ but
argument is of type ‘PetscInt (*)(struct _p_TS *, PetscReal, struct _p_Vec *,
struct _p_Vec *, struct _p_Vec *, void *, struct _p_Vec *)’
--
What most experimenters take for granted before they begin their experiments is
infinitely more interesting than any results to which their experiments lead.
-- Norbert Wiener
