nonlinear solvers

Matthew Knepley knepley at
Mon Feb 12 21:23:49 CST 2007

On 2/12/07, Manav Bhatia <bhatiamanav at> wrote:
> Hi,
>    I am using the nonlinear solvers in Petsc. My application requires
> the jacobian at the final nonlinear solution, since after the
> nonlinear solution I solve a linear system of equations with the
> jacobian as the system matrix.
>    I am curious to know if it is safe to assume that for all
> nonlinear solvers in Petsc, the last jacobian used before convergence
> is same as the jacobian evaluated at the final solution. If this is
> the case, then I will not need to evaluate the jacobian again,
> otherwise, I will need to compute it again after the final solution.

Never. We solve the Newton Equation, update the solution, and
THEN check for convergence. The Jacobian would not be updated.


>    Kindly help me with your comments.
> Thanks,
> Manav

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and critically is forced to realize that there are scarcely any bars to eventual
publication. There seems to be no study too fragmented, no hypothesis too
trivial, no literature citation too biased or too egotistical, no design too
warped, no methodology too bungled, no presentation of results too
inaccurate, too obscure, and too contradictory, no analysis too self-serving,
no argument too circular, no conclusions too trifling or too unjustified, and
no grammar and syntax too offensive for a paper to end up in print. --
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