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+#!/usr/bin/env python3
+
+import numpy as np
+import matplotlib.pyplot as plt
+import time
+import multiprocessing as mp
+from multiprocessing import RawArray
+
+# c-mesh limits
+limitre = ( -2, 1 )
+limitim = ( -1.5, 1.5 )
+
+
+def worker(gridchunk, s, step, T, l):
+ global rs
+ # Preallocate z array
+ rschunk = rs[s : s + step]
+
+ z = np.zeros(rschunk.shape)
+ print(f"rschunk.shape: {rschunk.shape}, gridchunk.shape: {gridchunk.shape}, T: {T}, l: {l}")
+
+ # Calculate ι for all complex numbers
+ for i in range(l):
+ # This will generate warnings for some of the values rising above T.
+ # Because these values are above T they are not used, thus the warnings
+ # can be ignored
+ z = z*z + gridchunk
+
+ # This will generate 1 in all the places
+ # where z < T and zeros elsewhere
+ below = (np.abs(z) < T)
+
+ # Add this to the result
+ # Because the ones that pass T are 0
+ # they will stop counting.
+ #
+ # If a specific z never reaches >= T its value in rs will
+ # be l
+ rschunk += below
+
+ np.divide(rschunk, l, out=rschunk)
+
+def mangel(pre, pim, T, l, workers):
+ """
+ Calculate the mangelbrot image with multiple processes
+ (pre, pim) discribes the image size. Use T and l to tune the mangelbrot
+
+ This will split the image in horizontal parts and distribute it
+ between the workers.
+ Because the result array is row major, data will be nicely together if
+ the workers work with rows not columns.
+
+ Pre must be devisible by workers.
+
+ The result is saved in rs. Sorry couln't get numpy references through to the process as arguments
+
+ :param pre: Number of real numbers used
+ :param pim: Number of imaginary numbers
+ :param T: Mangelbrot threshold
+ :param l: Iterations
+ :param workers: Number of workers.
+ """
+
+ # Used to calculate c-mesh
+ re = np.linspace(limitre[0], limitre[1], pre)
+ im = np.linspace(limitim[0], limitim[1], pim)
+
+ # Calculate c-mesh
+ grid = np.add.outer(re, 1j * im)
+
+ # Calculate the partition variables
+ step = int(pre / workers)
+
+
+ # Loop chunks and start the workers
+ wl = []
+ for s in range(0, pre, step):
+ gridchunk = grid[s : s + step]
+ p = mp.Process(target=worker, args=(gridchunk, s, step, T, l))
+ wl.append(p)
+ p.start()
+
+ # Wait for them to be done
+ for p in wl:
+ p.join()
+
+ return rs
+
+rs = np.full((500, 500), 0.5)
+
+start = time.time()
+arr = mangel(500, 500, 2, 100, 1)
+end = time.time()
+
+plt.imshow(arr, cmap=plt.cm.hot, vmin=0, vmax=1)
+plt.savefig("mult.png")
+
+print(f"Took {end - start} seconds")
+"""
+ p = mp.Process(target=worker, args=(rs[s:s + step], grid[s:s + step], T, l))
+ wl.append(p)
+ p.start()
+
+ # Wait for them to be done
+ for p in wl:
+ p.join()
+"""