2.9. Integral PI (with @reduction)

1.1 Initialize PyCOMPSs

import pycompss.interactive as ipycompss

import os
if 'BINDER_SERVICE_HOST' in os.environ:
    ipycompss.start(graph=True,                # trace=True
                   project_xml='../xml/project.xml',
                    resources_xml='../xml/resources.xml')
else:
    ipycompss.start(graph=True, monitor=1000, debug=True)  # trace=True

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**************** PyCOMPSs Interactive ******************
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* - Starting COMPSs runtime...                         *
* - Log path : /home/user/.COMPSs/Interactive_22/
* - PyCOMPSs Runtime started... Have fun!              *
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1.2 Required imports

from pycompss.api.api import compss_wait_on
from pycompss.api.task import task
from pycompss.api.reduction import reduction
from pycompss.api.parameter import *

2 Tasks Declaration

import numpy as np

@task(returns=float)
def calculate_area(i, num_steps, number_of_batches, step_size):
    partial_area_sum = 0
    for i in range(i, num_steps, number_of_batches):
        x = (i+0.5) * step_size
        partial_area_sum += 4 / (1 + x**2)
    return partial_area_sum

@reduction(chunk_size="2")
@task(returns=float, batches_partial_areas=COLLECTION_IN)
def sum_reduction(batches_partial_areas):
    total_area = 0
    for partial_area in batches_partial_areas:
        total_area += partial_area
    return total_area

Run the algorithm

num_steps = 100000
number_of_batches = 10

step_size = 1 / num_steps

batches_partial_areas = []
for i in range(number_of_batches):
    partial_area = calculate_area(i, num_steps, number_of_batches, step_size)
    batches_partial_areas.append(partial_area)


total_area = sum_reduction(batches_partial_areas)

Task definition detected.
Found task: calculate_area
Task definition detected.
Found task: sum_reduction

Wait for all tasks to finish and gather the result

total_area = compss_wait_on(total_area)

Calculate PI

pi = step_size * total_area

print('PI:', pi, 'Error:', abs(np.pi-pi))

PI: 3.141592653598127 Error: 8.333778112046275e-12

ipycompss.stop()

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***************** STOPPING PyCOMPSs ********************
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Checking if any issue happened.
Warning: some of the variables used with PyCOMPSs may
         have not been brought to the master.
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