[CIG-SHORT] Linear system solve

[Birendra jha]

Dear developers,

I have a question about KSPSolve in,

  err = KSPSolve(_ksp, residualVec, solutionVec); CHECK_PETSC_ERROR(err);

called inside,

pylith::problems::SolverLinear::solve(
                  topology::Field<topology::Mesh>* solution,
                  topology::Jacobian* jacobian,
                  const topology::Field<topology::Mesh>& residual)

I find that for same residualVec and jacobian matrix, my solutionVec (i.e. dispIncr) changes. What could be the reason? Does KSPSolve do anything other than solving Ax=b system, after it's provided with A and b?

I checked the jacobian in Implicit.py:step() using self.jacobian.view(), before the call to solve() is made. I checked residualVec and solutionVec using VecView(solutionVec,PETSC_VIEWER_STDOUT_WORLD) inside the SolverLinear::solve().

Boundary conditions are independent of time. Compression on two side boundaries, and nothing specified for other two sides which means traction-free surface, is that correct?
 
Thanks and best regards
Birendra