petsc-3.14.5 2021-03-03
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# TSSetTolerances

Set tolerances for local truncation error when using adaptive controller

### Synopsis

    #include "petscts.h"
    PetscErrorCode TSSetTolerances(TS ts,PetscReal atol,Vec vatol,PetscReal rtol,Vec vrtol)

Logically Collective

### Input Arguments

| ts | - time integration context
| atol | - scalar absolute tolerances, PETSC_DECIDE to leave current value
| vatol | - vector of absolute tolerances or NULL, used in preference to atol if present
| rtol | - scalar relative tolerances, PETSC_DECIDE to leave current value
| vrtol | - vector of relative tolerances or NULL, used in preference to atol if present

### Options Database keys

| -ts_rtol <rtol> | - relative tolerance for local truncation error
| -ts_atol <atol> Absolute tolerance for local truncation error

### Notes

With PETSc's implicit schemes for DAE problems, the calculation of the local truncation error (LTE) includes both the differential and the algebraic variables. If one wants the LTE to be computed only for the differential or the algebraic part then this can be done using the vector of tolerances vatol. For example, by setting the tolerance vector with the desired tolerance for the differential part and infinity for the algebraic part, the LTE calculation will include only the differential variables.

### See Also

TS, TSAdapt, TSErrorWeightedNorm(), TSGetTolerances()

### Level

beginner

### Location

src/ts/interface/ts.c

### Examples

src/ts/tutorials/ex49.c.html
src/ts/tutorials/ex50.c.html
src/tao/unconstrained/tutorials/spectraladjointassimilation.c.html
Index of all TS routines
Table of Contents for all manual pages
Index of all manual pages