petsc-3.14.5 2021-03-03
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# PetscDSGetExactSolutionTimeDerivative

Get the pointwise time derivative of the exact solution function for a given test field

### Synopsis

    #include "petscds.h"
    PetscErrorCode PetscDSGetExactSolutionTimeDerivative(PetscDS prob, PetscInt f, PetscErrorCode (**sol)(PetscInt dim, PetscReal t, const PetscReal x[], PetscInt Nc, PetscScalar u[], void *ctx), void **ctx)

Not collective

### Input Parameters

| prob | - The PetscDS
| f | - The test field number

### Output Parameter

| exactSol | - time derivative of the exact solution for the test field
| exactCtx | - time derivative of the exact solution context

### Note: The calling sequence for the solution functions is given by

    sol(PetscInt dim, PetscReal t, const PetscReal x[], PetscInt Nc, PetscScalar u[], void *ctx)

| dim | - the spatial dimension
| t | - current time
| x | - coordinates of the current point
| Nc | - the number of field components
| u | - the solution field evaluated at the current point
| ctx | - a user context

### See Also

PetscDSSetExactSolutionTimeDerivative(), PetscDSGetExactSolution()

### Level

intermediate

### Location

src/dm/dt/interface/dtds.c
Index of all DT routines
Table of Contents for all manual pages
Index of all manual pages