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# TSI2FunctionFn

A prototype of a `TS` implicit function evaluation function for 2nd order systems that would be passed to `TSSetI2Function()`

## Synopsis

    #include <petscts.h>
    PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(TSI2FunctionFn)(TS ts, PetscReal t, Vec U, Vec U_t, Vec U_tt, Vec F, void *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

- F - function vector

- ctx - [optional] user-defined context for matrix evaluation routine (may be `NULL`)

## Note

The deprecated `TSI2Function` still works as a replacement for `TSI2FunctionFn` *.

## See Also

TS: Scalable ODE and DAE Solvers, `TS`, `TSSetI2Function()`, `DMTSSetI2Function()`, `TSIFunctionFn`

## Level

advanced

## Location

include/petscts.h

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