Reduction operations take multiple values and reduce them to a single value. Common reduction operations include finding the maximum/minimum value, summing/multiplying all elements, or applying an associative binary operator. PVM supports reductions using the pvm_reduce() function, which takes parameters like the reduction function, data array, data type, group name, and root process. An example shows summing the elements of an array across three tasks in a group, with the results returned to the root task.

1. WELCOME

2. M.SOLAI RANI
II MSC(C S)
REDUCTION OPERATION

3. Reduction operation is use the multiple value are reduce into a single
value. It contain the maximum (minimum) value, the summation
(product) of all elements, Or the result of applying an associative
binary operator that yields a single result.
PVM is support the reduction. It use the pvm_reduce() function.
(Info + pvm_reduce ( func, data, n, datatype, tag, group_name, root)

4. Parameters for Reduction Operations
Parameter Meaning
func The function that defines the
operation to be performed.
data An array of data elements.
n The number of elements in the data
array.
datatype The type of entries in the data array.
tag Message tag.
group_name The name of an existing group.
root Instance number of a group member
who gets the result.

5. The reduction value for each element in the array across the group
will be returned to the root specified in the parameters. In fact, the
data array on the root will be overwritten with the result of the
reduction operation over the group. Users can define their own
functions or can use several PVM predefined functions such as
PVMMin, PVMMax, and PVMProduct for the minimum, maximum,
summation, and product, respectively.

6. Example 6 Figure 8.8 shows an example of a reduction summation of the entries
of data_array over the group “slave”, which has three members: T0,T1, and T2.
The reduced values are returned to the root, which is assumed to be task
T1 in this example. The following function must be called by the three tasks.
Info = pvm_reduce (PVMSum, data_array, 5, PVM_INT, tag, “slave”, root)
T0
T1(root
)
T2
10 5 20 8 30
2 15 4 12 6
8 25 6 10 24 8 25 6 10 14
20 45 30 30 50
10 5 20 8 30
Group: slave Before reduction After reduction
Info = pvm_reduce (PvmSum, data_array, 5, PVM_INT, tag, “salve”.
Reduction operation on th members of the group slave.

7. THNKYOU