Add test for infinite potential well

3 files changed, 53 insertions, 0 deletions

diff --git a/test/__init__.py b/test/__init__.py
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/test/__init__.py
@@ -0,0 +1 @@
+
diff --git a/test/infinite.inp b/test/infinite.inp
new file mode 100644
index 0000000..a61ffbe
--- /dev/null
+++ b/test/infinite.inp
@@ -0,0 +1,7 @@
+2.0             # mass
+-2.0 2.0 1999   # xMin xMax nPoint
+1 5             # first and last eigenvalue to print
+linear          # interpolation type
+2               # nr. of interpolation points and xy declarations
+-2.0 0.0
+2.0 0.0
diff --git a/test/test_infinite.py b/test/test_infinite.py
new file mode 100644
index 0000000..aa85ae5
--- /dev/null
+++ b/test/test_infinite.py
@@ -0,0 +1,45 @@
+import pytest
+import numpy as np
+
+import matplotlib.pyplot as plt
+
+from schroedinger import (
+    Config, potential_interp, build_potential, solve_schroedinger
+)
+
+
+def psi(x, n, a):
+    n += 1 # Index starting from 0
+    x = -x + a / 2 # Reflect x and move to the left
+    return np.sqrt(2 / a) * np.sin(n * np.pi * x / a)
+
+
+def energy(n, a, m):
+    return (n + 1)**2 * np.pi**2 / m / a**2 / 2.0
+
+
+def test_infinite():
+    conf = Config('test/infinite.inp')
+    potential, delta = build_potential(conf)
+
+    e, v = solve_schroedinger(conf.mass, potential[:, 1], delta, conf.eig_interval)
+    # Account for -v also being an eigenvector if v is one
+    v = np.abs(v)
+
+    a = np.abs(conf.points[1][0] - conf.points[0][0])
+    e_theory = np.zeros(e.shape)
+    v_theory = np.zeros(v.shape)
+
+
+    for n in range(e.shape[0]):
+        e_theory[n] = energy(n, a, conf.mass)
+        v_theory[:, n] = np.abs(psi(potential[:, 0], n, a))
+
+    # for n in range(e.shape[0]):
+    #     plt.plot(potential[:, 0], np.abs(v[:, n]), label='Num{}'.format(n))
+    #     plt.plot(potential[:, 0], np.abs(v_theory[:, n]), ls='--', label='Theory{}'.format(n))
+    # plt.legend()
+    # plt.savefig('test.pdf')
+
+    assert (np.allclose(e, e_theory, rtol=1e-2, atol=1e-2)
+            and np.allclose(v, v_theory, rtol=1e-2, atol=1e-2))