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POmulti-threading of a matrix multiplication in python
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  1. POmulti-threading of a matrix multiplication in python
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    copied!<p>I want to create n threads and that each thread computes an entire row of the result matrix. I have tried the following code,</p> <pre><code>import numpy import random import threading class MatrixMult(threading.Thread): """A thread which computes the i,j entry of A * B""" def __init__(self, A, B, i): super(MatrixMult, self).__init__() self.A = A self.B = B self.i = i #self.j = j def run(self): print "Computing %i, %i" % (self.i, self.i) x = 0 result=[] for k in range(self.A.shape[0]) x += self.A[self.i,k] * self.B[k,self.i self.result=x print "Completed %i, %i" % (self.i, self.j) def mult(n): """A function to randomly create two n x n matrices and multiply them""" # Create two random matrices A = numpy.zeros((n,n)) B = numpy.zeros((n,n)) for i in range(n): for j in range(n): A[i,j] = random.randrange(0, 100) B[i,j] = random.randrange(0, 100) # Create and start the threads threads = [] for i in range(n): # for j in range(n): t = MatrixMult(A, B, i) threads.append(t) t.start() for t in threads: t.join() C = numpy.zeros((n,n)) for t in threads: C[t.i] = t.result return C print multi(30) </code></pre> <p>however it prints out many weird matrices:</p> <pre><code>[ 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695. 66695.] [ 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468. 88468.]] </code></pre> <p>anyone see a problem in my code? I don't see what i am doing wrong.</p>
 

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