function
   
petsc-3.5.4 2015-05-23
[flg,err] = nljacobian(snes,x,A,B,ctx) % % Example of a nonlinear Jacobian needed by SNES % Use identity as approximation for Jacobian % err = 0; flg = PetscMat.SAME_NONZERO_PATTERN; for i=1:10 B.SetValues(i,i,1.0); end err = B.AssemblyBegin(PetscMat.FINAL_ASSEMBLY); err = B.AssemblyEnd(PetscMat.FINAL_ASSEMBLY); err = A.AssemblyBegin(PetscMat.FINAL_ASSEMBLY); err = A.AssemblyEnd(PetscMat.FINAL_ASSEMBLY);