[petsc-users] how to get the differencing paramter in a matrix free formulation

[Kontsantinos Kontzialis]

Dear all,

  I'm using the following function:

ierr = MatMFFDGetH(sys.J, &h);
     CHKERRQ(ierr);

to get the parameter h in the formula for the jacobian-vector product, 
but it returns a value of 0. But how can that be, otherwise a division 
by zero would result.

Thank you,

Costas