# PetscViewerHDF5PushTimestepping
Activate timestepping mode for subsequent HDF5 reading and writing. 
## Synopsis
```
#include "petscviewerhdf5.h" 
PetscErrorCode PetscViewerHDF5PushTimestepping(PetscViewer viewer)
```
Not collective


## Input Parameter

- ***viewer -*** the `PetscViewer` of type `PETSCVIEWERHDF5`





## Notes
On first `PetscViewerHDF5PushTimestepping()`, the initial time step is set to 0.
Next timesteps can then be set using `PetscViewerHDF5IncrementTimestep()` or `PetscViewerHDF5SetTimestep()`.
Current timestep value determines which timestep is read from or written to any dataset on the next HDF5 I/O operation [e.g. `VecView()`].
Use `PetscViewerHDF5PopTimestepping()` to deactivate timestepping mode; calling it by the end of the program is NOT mandatory.
Current timestep is remembered between `PetscViewerHDF5PopTimestepping()` and the next `PetscViewerHDF5PushTimestepping()`.

If a dataset was stored with timestepping, it can be loaded only in the timestepping mode again.
Loading a timestepped dataset with timestepping disabled, or vice-versa results in an error.


## Developer note
Timestepped HDF5 dataset has an extra dimension and attribute "timestepping" set to true.


## See Also
 [](sec_viewers), `PETSCVIEWERHDF5`, `PetscViewerHDF5Open()`, `PetscViewerHDF5PopTimestepping()`, `PetscViewerHDF5IsTimestepping()`, `PetscViewerHDF5SetTimestep()`, `PetscViewerHDF5IncrementTimestep()`, `PetscViewerHDF5GetTimestep()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/sys/classes/viewer/impls/hdf5/hdf5v.c.html#PetscViewerHDF5PushTimestepping">src/sys/classes/viewer/impls/hdf5/hdf5v.c</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/tutorials/ex19.c.html">src/vec/vec/tutorials/ex19.c.html</A><BR>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/sys/classes/viewer/impls/hdf5/hdf5v.c)


[Index of all Viewer routines](index.md)  
[Table of Contents for all manual pages](/docs/manualpages/index.md)  
[Index of all manual pages](/docs/manualpages/singleindex.md)  
