Stefano Zampini <[email protected]> writes:

> 2017-07-24 19:28 GMT+03:00 Barry Smith <[email protected]>:
>
>>
>>
>> >
>> > IMHO I think that it is not worth the complication. I value the
>> generality of the current API, that already is somewhat cumbersome to
>> maintain.
>> > Users providing the RHS function + mass matrix already know that they
>> should do M^-1 * rhsvec to compute the rhs function.
>>
>>    Then they get wrong or confusing information with TSAdjoint, not a good
>> thing.
>>
>>
> Barry,
>
> it seems to me that in order to get a gradient for PDE constrained
> optimization out of TS, we need to be able to evaluate separately the two
> PDE gradients \nabla_x F and \nabla_xp F, where F() is the time dependent
> PDE in implicit form, i.e. F(x,xp,t) = 0, with xp the time derivative of
> the state.

In what circumstances do we need these separately, versus the weighted
sum that IJacobian produces?

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