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# TSI2JacobianFn

A prototype of a `TS` implicit Jacobian evaluation function for 2nd order systems that would be passed to `TSSetI2Jacobian()`

## Synopsis

    #include <petscts.h>
    PETSC_EXTERN_TYPEDEF typedef PetscErrorCode TSI2JacobianFn(TS ts, PetscReal t, Vec U, Vec U_t, Vec U_tt, PetscReal v, PetscReal a, Mat J, Mat Jac, PetscCtx ctx);

## Calling Sequence

- ts - the `TS` context obtained from `TSCreate()`

- t - time at step/stage being solved

- U - state vector

- U_t - time derivative of state vector

- U_tt - second time derivative of state vector

- v - shift for U_t

- a - shift for U_tt

- J - Jacobian of G(U) = F(t,U,W+vU,W’+aU), equivalent to dF/dU + vdF/dU_t + adF/dU_tt

- jac - matrix from which to construct the preconditioner, may be same as `J`

- ctx - [optional] user-defined context for matrix evaluation routine

## Note

The deprecated `TSI2Jacobian` still works as a replacement for `TSI2JacobianFn` *.

## See Also

TS: Scalable ODE and DAE Solvers, `TS`, `TSSetI2Jacobian()`, `DMTSSetI2Jacobian()`, `TSIFunctionFn`, `TSIJacobianFn`, `TSRHSFunctionFn`, `TSRHSJacobianFn`

## Level

advanced

## Location

include/petscts.h

Index of all TS routines
Table of Contents for all manual pages
Index of all manual pages