A reduction operation that combines two values to produce a third value.

**Namespace:**
MPI

**Assembly:**
MPI (in MPI.dll)**Version:** 1.0.0.0 (1.0.0.0)

# Syntax

C# |
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public delegate T ReductionOperation<T>( T x, T y ) |

Visual Basic (Declaration) |
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Public Delegate Function ReductionOperation(Of T) ( _ x As T, _ y As T _ ) As T |

Visual C++ |
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generic<typename T> public delegate T ReductionOperation( T x, T y ) |

#### Parameters

- x
- Type: T

- y
- Type: T

# Type Parameters

- T

# Remarks

Reduction operations are used by various collective operations such as
Allreduce<(Of <(T>)>)(T, ReductionOperation<(Of <(T>)>)).
Note that any operation used as a reduction operation must be associative,
e.g., op(x, op(y, z)) == op(op(x, y), z). These operations need not be
commutative.