From ff5eeb66b446fc3f2b61b8b0034f14be41b6555c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Kn=C3=BCttel?= <daniel.knuettel@daknuett.eu>
Date: Tue, 19 Feb 2019 14:13:46 +0100
Subject: [PATCH] added ex24

---
 exam/ex24/main.py | 64 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)
 create mode 100644 exam/ex24/main.py

diff --git a/exam/ex24/main.py b/exam/ex24/main.py
new file mode 100644
index 0000000..826920b
--- /dev/null
+++ b/exam/ex24/main.py
@@ -0,0 +1,64 @@
+import sys
+sys.path.append("../../")
+
+import numpy as np
+import matplotlib.pyplot as plt
+import matplotlib.animation as animation
+
+from util.io import readvalue
+
+def positive_int(s):
+	i = int(s)
+	if(not i > 0):
+		raise ValueError("{} <= 0".format(i))
+	return i
+
+def prepare_A(n):
+	A = -2 * np.identity(n)
+	A += np.roll(np.identity(n), 1, axis=0)
+	A += np.roll(np.identity(n), -1, axis=0)
+	return A
+
+N = readvalue("N > ", positive_int)
+M = readvalue("M > ", positive_int)
+kappa = 0.05
+
+A = prepare_A(N)
+eigenvalues, eigenvectors = np.linalg.eigh(A)
+
+#print(*zip(*enumerate(eigenvalues)))
+plt.scatter(*zip(*enumerate(eigenvalues)))
+plt.savefig("output/eigenvalues.png")
+
+plt.clf()
+
+for n in range(N):
+	plt.scatter(*zip(*enumerate(eigenvectors[n])))
+	plt.savefig("output/eigenvector_{}.png".format(n))
+	plt.clf()
+
+v = np.zeros(N)
+v[0] = 1
+
+
+fig, ax = plt.subplots()
+max_eigv, = ax.plot(*zip(*enumerate(eigenvectors[0])), "bo")
+scatter, = ax.plot(*zip(*enumerate(v)), "ro")
+
+def on_tick(data):
+	global v
+	v = (np.identity(N) + kappa*A).dot(v)
+	scatter.set_data(*zip(*enumerate(v)))
+
+	return scatter
+
+def run():
+	for i in range(M):
+		yield i
+
+
+ani = animation.FuncAnimation(fig, on_tick, run, interval=1)
+ani.save("output/animation.gif", dpi=80, writer='imagemagick')
+
+
+