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Teuchos - Trilinos Tools Package
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Teuchos - Trilinos Tools Package
Version of the Day
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Teuchos version of MPI_MAXLOC. More...
Public Member Functions | |
| void | reduce (const Ordinal count, const std::pair< ScalarType, IndexType > inBuffer[], std::pair< ScalarType, IndexType > inoutBuffer[]) const |
 Public Member Functions inherited from Teuchos::Describable | |
| virtual std::string | description () const |
| Return a simple one-line description of this object. More... | |
| virtual void | describe (FancyOStream &out, const EVerbosityLevel verbLevel=verbLevel_default) const |
| Print the object with some verbosity level to a FancyOStream. More... | |
| void | describe (std::ostream &out, const EVerbosityLevel verbLevel=verbLevel_default) const |
| Version of describe() that takes an std::ostream instead of a FancyOStream. More... | |
| virtual | ~Describable () |
| Destructor (marked virtual for memory safety of derived classes). More... | |
| Public Member Functions inherited from Teuchos::LabeledObject | |
| LabeledObject () | |
| Construct with an empty label. More... | |
| virtual | ~LabeledObject () |
| virtual void | setObjectLabel (const std::string &objectLabel) |
| Set the object label (see LabeledObject). More... | |
| virtual std::string | getObjectLabel () const |
| Get the object label (see LabeledObject). More... | |
Additional Inherited Members | |
| Static Public Attributes inherited from Teuchos::Describable | |
| static const EVerbosityLevel | verbLevel_default = VERB_DEFAULT |
Default value for the verbLevel argument of describe(). More... | |
| Related Functions inherited from Teuchos::Describable | |
| DescribableStreamManipulatorState | describe (const Describable &describable, const EVerbosityLevel verbLevel=Describable::verbLevel_default) |
| Describable output stream manipulator. More... | |
| std::ostream & | operator<< (std::ostream &os, const DescribableStreamManipulatorState &d) |
| Output stream operator for Describable manipulator. More... | |
Teuchos version of MPI_MAXLOC.
| Ordinal | The template parameter of Comm. |
| ScalarType | Type for which to find the maximum. |
| IndexType | Type indicating the index of the maximum. |
MPI_MAXLOC is a standard reduction operator provided by the MPI standard. According to the standard, MPI_MAXLOC combines the (value, index) pairs (u,i) and (v,j) into (w,j), where 
, and
![\[ k = \begin{cases} i & \text{if $u > v$}, \\ \min(i,j) & \text{if $u = v$}, \\ j & \text{if $u < v$}. \\ \end{cases} \]](form_4.png)
This class implements the MPI_MAXLOC reduction operator for the Teuchos communication wrappers. We need to define this separately from MPI for two reasons. First, the Teuchos comm wrappers do not currently expose taking an MPI_Op. Second, we need MaxLoc to be templated on the scalar and index types, in order to match Teuchos' MPI interface.
What happens to NaN ("Not a Number")? A NaN is neither less than, greater than, or equal to any floating-point number or any NaN. We can alter the above definition slightly so that a MaxLoc reduction has a well-defined result in case the array contains a NaN:
![\[ w = \begin{cases} u & \text{if $u > v$}, \\ v & \text{if $u < v$}. \\ u & \text{otherwise}. \\ \end{cases} \]](form_5.png)
and
![\[ k = \begin{cases} i & \text{if $u > v$}, \\ j & \text{if $u < v$}. \\ \min(i,j) & \text{otherwise}. \\ \end{cases} \]](form_6.png)
Defining MaxLoc in this way ensures that for any array containing a NaN, the value (w) returned is the first NaN, and the index (k) returned is the index of the first NaN.
Definition at line 79 of file Teuchos_TimeMonitor.cpp.
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virtual |
1.8.5