﻿Reduce(T) Method (T[], ReductionOperation(T), Int32)

[This is preliminary documentation and is subject to change.]

Reducec> is a collective algorithm that combines the values stored by each process into a single value available at the designated root process. This particular variant of Reduce<(Of <(T>)>)(T, ReductionOperation<(Of <(T>)>), Int32) applies to each of the elements of the provided arrays. Each process must provide arrays of the same length, and the values at each array index are combined in a user-defined way, specified via a delegate. If value1, value2, ..., valueN are the ith values provided by the N processes in the communicator, the ith result will be the value value1 op value2 op ... op valueN. The resulting array is only available to the root process. If all processes need the result of the reduction, use Allreduce<(Of <(T>)>)(array<T>[]()[], ReductionOperation<(Of <(T>)>), array<T>[]()[]%).

Namespace:  MPI
Assembly:  MPI (in MPI.dll)
Version: 0.8.0.0 (0.8.0.0)

# Syntax

C#
```public T[] Reduce<T>(
T[] values,
ReductionOperation<T> op,
int root
)```
Visual Basic (Declaration)
```Public Function Reduce(Of T) ( _
values As T(), _
op As ReductionOperation(Of T), _
root As Integer _
) As T()```
Visual C++
```public:
generic<typename T>
array<T>^ Reduce(
array<T>^ values,
ReductionOperation<T>^ op,
int root
)```

#### Parameters

values
Type: array< T >[]()[]
The local values that will be combined with the values provided by other processes.
op
Type: MPI..::.ReductionOperation<(Of <(T>)>)
The operation used to combine two values. This operation must be associative.
root
Type: System..::.Int32
The rank of the process that is the root of the reduction operation, to which this routine will return the result of the reduction operation.

# Type Parameters

T
Any serializable type.

#### Return Value

On the root, an array that contains the result of elementwise reduction on the values arrays provided by each process. On all other processes, null.