# PetscBool3
Ternary logical variable. Actually an enum in C and a 4 byte integer in Fortran. 
## Synopsis
```
typedef enum {
  PETSC_BOOL3_FALSE,
  PETSC_BOOL3_TRUE,
  PETSC_BOOL3_UNKNOWN = -1
} PetscBool3;
```



## Note
Should not be used with the if (flg) or if (!flg) syntax.


## See Also
 `PETSC_TRUE`, `PETSC_FALSE`, `PetscNot()`, `PETSC_BOOL3_TRUE`, `PETSC_BOOL3_FALSE`, `PETSC_BOOL3_UNKNOWN`

## Level
beginner

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/include/petscsystypes.h.html#PetscBool3">include/petscsystypes.h</A>


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