# PetscUnlikely
Hints the compiler that the given condition is usually false 
## Synopsis
```
#include <petscmacros.h>
bool PetscUnlikely(bool cond)
```
Not Collective


## Input Parameter

- ***cond -*** Boolean expression



## Notes
Not available from fortran.

This returns the same truth value, it is only a hint to compilers that the result of cond is
unlikely to be true.


## Example usage
```none
  if (PetscUnlikely(cond)) {
    foo(); // cold path
  } else {
    bar(); // hot path
  }
```





## See Also
 `PetscLikely()`, `PetscUnlikelyDebug()`, `PetscCall()`, `PetscDefined()`, `PetscHasAttribute()`,
`PETSC_ATTRIBUTE_COLD`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/include/petscmacros.h.html#PetscUnlikely">include/petscmacros.h</A>


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