Cluster ising.py
From Werner KRAUTH
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- | This page presents the program markov_disks_box.py, a Markov-chain algorithm for four disks in a square box of sides 1. | + | This page presents the program cluster_ising.py, the Wolff cluster algorithm for the Ising model on an LxL square lattice in two dimensions |
__FORCETOC__ | __FORCETOC__ | ||
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=Program= | =Program= | ||
- | import random | ||
- | |||
- | L = [[0.25, 0.25], [0.75, 0.25], [0.25, 0.75], [0.75, 0.75]] | ||
- | sigma = 0.15 | ||
- | sigma_sq = sigma ** 2 | ||
- | delta = 0.1 | ||
- | n_steps = 1000 | ||
- | for steps in range(n_steps): | ||
- | a = random.choice(L) | ||
- | b = [a[0] + random.uniform(-delta, delta), a[1] + random.uniform(-delta, delta)] | ||
- | min_dist = min((b[0] - c[0]) ** 2 + (b[1] - c[1]) ** 2 for c in L if c != a) | ||
- | box_cond = min(b[0], b[1]) < sigma or max(b[0], b[1]) > 1.0 - sigma | ||
- | if not (box_cond or min_dist < 4.0 * sigma ** 2): | ||
- | a[:] = b | ||
- | print L | ||
- | =Version= | ||
- | See history for version information. | ||
- | |||
- | [[Category:Python]] | ||
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for j in Cluster: | for j in Cluster: | ||
S[j] *= -1 | S[j] *= -1 | ||
+ | |||
+ | |||
+ | =Version= | ||
+ | See history for version information. | ||
+ | |||
+ | [[Category:Python]] [[Category:Honnef_2015]] [[Category:MOOC_SMAC]] |
Revision as of 21:50, 22 September 2015
This page presents the program cluster_ising.py, the Wolff cluster algorithm for the Ising model on an LxL square lattice in two dimensions
Contents |
Description
Program
import random, math L = 100 N = L * L nbr = {i : ((i // L) * L + (i + 1) % L, (i + L) % N, (i // L) * L + (i - 1) % L, (i - L) % N) for i in range(N)} T = 2.5 p = 1.0 - math.exp(-2.0 / T) nsteps = 10000 S = [random.choice([1, -1]) for k in range(N)] for step in range(nsteps): k = random.randint(0, N - 1) Pocket, Cluster = [k], [k] while Pocket != []: j = random.choice(Pocket) for l in nbr[j]: if S[l] == S[j] and l not in Cluster \ and random.uniform(0.0, 1.0) < p: Pocket.append(l) Cluster.append(l) Pocket.remove(j) for j in Cluster: S[j] *= -1
Version
See history for version information.