What version of PETSc are you using and are you using the standard precision and scalar so that PetscScalar is double precision?
Also what Fortran compiler? Barry > On Aug 16, 2019, at 11:21 AM, José Lorenzo via petsc-users > <[email protected]> wrote: > > Hello, > > I am struggling with a strange error when using VecAXPY. I have a ghost > vector H that needs to be updated as > > H = H + eta * dH - eta_old * dH > > However, for some reason I obtain different results when using > > call VecAXPY(H, eta - eta_old, dH, ierr) > > instead of > > call VecAXPY(H, - eta_old, dH, ierr) > > call VecAXPY(H, eta, dH, ierr) > > where eta and eta_old are PetscScalars. > > The first option seems to provide a wrong output, but I do not understand > what can go wrong in such simple operation. > > Thank you. >
