[petsc-users] TSSetIFunction

[Jin, Shuangshuang]

As a test, I changed the line “  f[1] = (x[1]*x[1]*x[1]/3 - x[1])-x[0];” to “f[1] = (PetscRealPart(x[1])*PetscRealPart(x[1])*PetscRealPart(x[1])/3 - PetscRealPart(x[1]))-PetscRealPart(x[0]);”, and it runs with the same results as I run ex19.c alone.

However, I don’t understand why I only need to change this line but leave nothing else such as the line before it “f[0] = xdot[0] + x[1];” unchanged?

And can anyone please tell me in ex19.c what does this part of code do?

  PetscErrorCode ierr;

  PetscFunctionBegin;
  {
    const PetscReal
      A[3][3] = {{0,0,0},
                 {0.41421356237309504880,0,0},
                 {0.75,0.25,0}},
      At[3][3] = {{0,0,0},
                  {0.12132034355964257320,0.29289321881345247560,0},
                  {0.20710678118654752440,0.50000000000000000000,0.29289321881345247560}};
      ierr = TSARKIMEXRegister("myark2",2,3,&At[0][0],PETSC_NULL,PETSC_NULL,&A[0][0],PETSC_NULL,PETSC_NULL,PETSC_NULL,PETSC_NULL,0,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
  }
  PetscFunctionReturn(0);

It seems to me an initialization of the A matrix. But I looked into TSARKIMEXRegister, still couldn’t understand how it works.

Thanks,
Shuangshuang

From: petsc-users-bounces at mcs.anl.gov [mailto:petsc-users-bounces at mcs.anl.gov] On Behalf Of Jin, Shuangshuang
Sent: Wednesday, March 20, 2013 4:18 PM
To: PETSc users list
Subject: Re: [petsc-users] TSSetIFunction

Thanks, I make the “IFunction” and “IJacobian” static in the header file and the mismatch goes away.

Another question is I know ex19.c is using real numbers only, if I run it alone, I should use arch-real to compile it successfully.
However, because my code has to do complex numbers computation somewhere else, I built the PETSc with an ARCH-complex. Now when I  integrate ex19.c into my code, I get the following compilation error:

[d3m956 at olympus ss00]$ make
mpicxx -I/pic/projects/ds/petsc-dev/include -I/pic/projects/ds/petsc-dev/arch-complex/include -I/share/apps/openmpi/1.5.4/gcc/4.1.2/include -g -c -o simulation.o simulation.C
simulation.C: In static member function ‘static PetscErrorCode Simulation::IFunction(_p_TS*, PetscReal, _p_Vec*, _p_Vec*, _p_Vec*, void*)’:
simulation.C:25: error: no match for ‘operator/’ in ‘std::operator* [with _Tp = double](((const std::complex<double>&)((const std::complex<double>*)(& std::operator* [with _Tp = double](((const std::complex<double>&)((const std::complex<double>*)(x + 16u))), ((const std::complex<double>&)((const std::complex<double>*)(x + 16u))))))), ((const std::complex<double>&)((const std::complex<double>*)(x + 16u)))) / 3’
make: *** [simulation.o] Error 1

I guess it is because of the complex number and real number mismatch. But I’m not sure if it’s the case.
simulation.C:25 corresponds to line  “f[1] = (x[1]*x[1]*x[1]/3 - x[1])-x[0];” in the code:

PetscErrorCode Simulation::IFunction(TS ts,PetscReal t,Vec X,Vec Xdot,Vec F,void *ctx)
{
  PetscErrorCode ierr;
  PetscScalar *x,*xdot,*f;

  PetscFunctionBegin;
  ierr = VecGetArray(X,&x);CHKERRQ(ierr);
  ierr = VecGetArray(Xdot,&xdot);CHKERRQ(ierr);
  ierr = VecGetArray(F,&f);CHKERRQ(ierr);
  f[0] = xdot[0] + x[1];
  f[1] = (x[1]*x[1]*x[1]/3 - x[1])-x[0];
  ierr = VecRestoreArray(X,&x);CHKERRQ(ierr);
  ierr = VecRestoreArray(Xdot,&xdot);CHKERRQ(ierr);
  ierr = VecRestoreArray(F,&f);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

Thanks,
Shuangshuang




From: petsc-users-bounces at mcs.anl.gov<mailto:petsc-users-bounces at mcs.anl.gov> [mailto:petsc-users-bounces at mcs.anl.gov] On Behalf Of Jed Brown
Sent: Wednesday, March 20, 2013 2:52 PM
To: PETSc users list
Subject: Re: [petsc-users] TSSetIFunction

You cannot use a member function as a callback. You can (with almost all compilers) use a _static_ member function. Note that static member functions do not have a "this" pointer. The void* argument in the callback should be set to the class so that you can use it as a "this" pointer.

On Wed, Mar 20, 2013 at 4:47 PM, Jin, Shuangshuang <Shuangshuang.Jin at pnnl.gov<mailto:Shuangshuang.Jin at pnnl.gov>> wrote:
Hi, I use src\ts\examples\tutorials\ex19.c as an example to use PETSc DAE solver. I get the following problem while running my code:

[d3m956 at olympus ss00]$ make
mpicxx -I/pic/projects/ds/petsc-dev/include -I/pic/projects/ds/petsc-dev/arch-complex/include -I/share/apps/openmpi/1.5.4/gcc/4.1.2/include -g -c -o simulation.o simulation.C
simulation.C: In member function ‘PetscErrorCode Simulation::simu(_p_Mat*, _p_Mat*, _p_Mat*)’:
simulation.C:80: error: argument of type ‘PetscErrorCode (Simulation::)(_p_TS*, PetscReal, _p_Vec*, _p_Vec*, _p_Vec*, void*)’ does not match ‘PetscErrorCode (*)(_p_TS*, PetscReal, _p_Vec*, _p_Vec*, _p_Vec*, void*)’
make: *** [simulation.o] Error 1

What does it mean?

The IFunction is copied from ex19.c,

PetscErrorCode Simulation::IFunction(TS ts,PetscReal t,Vec X,Vec Xdot,Vec F,void *ctx)
{
  PetscErrorCode ierr;
  PetscScalar *x,*xdot,*f;

  PetscFunctionBegin;
  ierr = VecGetArray(X,&x);CHKERRQ(ierr);
  ierr = VecGetArray(Xdot,&xdot);CHKERRQ(ierr);
  ierr = VecGetArray(F,&f);CHKERRQ(ierr);
  f[0] = xdot[0] + x[1];
  f[1] = (x[1]*x[1]*x[1]/3 - x[1])-x[0];
  ierr = VecRestoreArray(X,&x);CHKERRQ(ierr);
  ierr = VecRestoreArray(Xdot,&xdot);CHKERRQ(ierr);
  ierr = VecRestoreArray(F,&f);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

And in Simulation::simu(Mat f1, Mat f2, Mat f3), I have:

ierr = TSSetIFunction(ts,NULL,IFunction,&user);CHKERRQ(ierr);

Thanks,
Shuangshuang



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