# PetscLogEventBegin
Logs the beginning of a user event. 
## Synopsis
```
#include <petsclog.h>
PetscErrorCode PetscLogEventBegin(int e,PetscObject o1,PetscObject o2,PetscObject o3,PetscObject o4)
```
Not Collective


## Input Parameters

- ***e -*** integer associated with the event obtained from PetscLogEventRegister()
- ***o1,o2,o3,o4 -*** objects associated with the event, or 0



## Fortran Synopsis
void PetscLogEventBegin(int e,PetscErrorCode ierr)


## Usage
```none
     PetscLogEvent USER_EVENT;
     PetscLogDouble user_event_flops;
     PetscLogEventRegister("User event",0,&USER_EVENT);
     PetscLogEventBegin(USER_EVENT,0,0,0,0);
        [code segment to monitor]
        PetscLogFlops(user_event_flops);
     PetscLogEventEnd(USER_EVENT,0,0,0,0);
```



## Developer Note
`PetscLogEventBegin()` and `PetscLogEventBegin()` return error codes instead of explicitly handling the
errors that occur in the macro directly because other packages that use this macros have used them in their
own functions or methods that do not return error codes and it would be disruptive to change the current
behavior.




## See Also
 `PetscLogEventRegister()`, `PetscLogEventEnd()`, `PetscLogFlops()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/sys/logging/plog.c.html#PetscLogEventBegin">src/sys/logging/plog.c</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/sys/classes/random/tutorials/ex1.c.html">src/sys/classes/random/tutorials/ex1.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/sys/tutorials/ex3.c.html">src/sys/tutorials/ex3.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/sys/tutorials/ex3f.F90.html">src/sys/tutorials/ex3f.F90.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/sys/tutorials/ex3f90.F90.html">src/sys/tutorials/ex3f90.F90.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/tutorials/ex10.c.html">src/vec/vec/tutorials/ex10.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/tutorials/ex15.c.html">src/vec/vec/tutorials/ex15.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/tutorials/ex5.c.html">src/vec/vec/tutorials/ex5.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/tutorials/ex5f.F90.html">src/vec/vec/tutorials/ex5f.F90.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/tutorials/ex5cu.cu.html">src/mat/tutorials/ex5cu.cu.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/tutorials/ex5k.kokkos.cxx.html">src/mat/tutorials/ex5k.kokkos.cxx.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex9.c.html">src/ksp/ksp/tutorials/ex9.c.html</A><BR>


---
[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/sys/logging/plog.c)


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