1 files changed, 79 insertions, 10 deletions
diff --git a/schroedinger/schroedinger.py b/schroedinger/schroedinger.py
index 63ea5f8..3ed2c3f 100644
--- a/schroedinger/schroedinger.py
+++ b/schroedinger/schroedinger.py
@@ -1,17 +1,86 @@
+from pathlib import Path
 
-def hello():
-    """
-    This is a description :)
-    :return:  None
-    """
-    print('Hello')
+import numpy as np
+from numpy.polynomial import Polynomial
+from numpy.typing import NDArray
+from scipy.interpolate import CubicSpline
+from scipy.linalg import eigh_tridiagonal
 
+class Config:
+    def __init__(self, path):
+        current_line = 0
 
-def main():
-    hello()
+        # Ensure Path object
+        if path is not Path:
+            path = Path(path)
 
+        def next_parameter(fd):
+            '''Read next parameter, ignoring comments or empty lines'''
+            content = None
+            nonlocal current_line
+            while not content:
+                str = fd.readline()
+                current_line += 1
+                index = str.find('#')
+                content = str[0:index].strip()
+            return content
 
+        with open(path, 'r') as fd:
+            try:
+                self.mass = float(next_parameter(fd))
+                start, end, steps = next_parameter(fd).split()
+                self.interval = [float(start), float(end), int(steps)]
+                self.eig_interval = [int(attr) - 1 for attr in next_parameter(fd).split()]
+                self.interpolation = next_parameter(fd)
 
-if __name__ == "__main__":
+                npoints = int(next_parameter(fd))
+                self.points = np.zeros((npoints, 2))
+                for i in range(npoints):
+                    line = next_parameter(fd)
+                    self.points[i] = np.array([float(comp) for comp in line.split()])
+            # TODO: don't be a moron, catch only relevant exceptions
+            except:
+                print('Syntax error in \'{}\' line {}'.format(path.name, current_line))
+                raise ValueError()
 
-    main()
+
+def potential_interp(interpolation, points):
+    if interpolation == 'linear':
+        def line(x):
+            return np.interp(x, points[:, 0], points[:, 1])
+        return line
+    elif interpolation == 'polynomial':
+        poly = Polynomial.fit(points[:, 0], points[:, 1],
+                              points.shape[0] - 1)
+        return poly
+    elif interpolation == 'cspline':
+        cs = CubicSpline(points[:, 0], points[:, 1])
+        return cs
+
+    raise ValueError()
+
+
+def build_potential(config: Config):
+    start, end, steps = config.interval
+    potential = np.zeros((steps, 2))
+    potential[:, 0] = np.linspace(start, end, steps)
+    delta = np.abs(potential[1, 0] - potential[0, 0])
+    interp = potential_interp(config.interpolation, config.points)
+    potential[:, 1] = interp(potential[:, 0])
+    return potential, delta
+
+
+def solve_schroedinger(mass, potential, delta, eig_interval=None):
+    '''
+    returns eigen values and wave functions specified by eig_interval
+    '''
+    n = potential.shape[0]
+    a = 1 / mass / delta**2
+    w, v = eigh_tridiagonal(a + potential,
+                            -a * np.ones(n - 1, dtype=np.float_) / 2.0,
+                            select='i', select_range=eig_interval)
+    # Normalize eigenfunctions
+    for i in range(w.shape[0]):
+        v[:, i] /= np.sqrt(delta * np.sum(np.abs(v[:, i])**2))
+
+    return w, v