Nutze Skyfield fuer praezisere Daemmerungsberechnung

public/py/vendor/skyfield/curvelib.py

@@ -0,0 +1,48 @@
+"""Various curves."""
+
+from numpy import arange
+from ._compatibility import interp
+from .descriptorlib import reify
+from .functions import _to_array
+
+class Splines(object):
+    def __init__(self, table):
+        table = _to_array(table)
+        if len(table.shape) < 2:  # Let caller provide a single row.
+            table = table.reshape(table.shape + (1,))
+        self.table = table
+        self.lower = lower = table[0]
+        self.upper = upper = table[1]
+        self._width = upper - lower
+        self._n = arange(len(lower))
+        self.coefficients = table[2:]
+
+    def __call__(self, x):
+        i = interp(x, self.lower, self._n)
+        i = i.astype(int)
+        t = (x - self.lower[i]) / self._width[i]
+        coefficients = iter(self.coefficients)
+        value = next(coefficients)[i]
+        for c in coefficients:
+            value *= t
+            value += c[i]
+        return value
+
+    @reify
+    def derivative(self):
+        columns = [self.table[0], self.table[1]]
+        coefficients = self.table[2:-1]
+        for i, c in enumerate(coefficients):
+            n = len(coefficients) - i
+            columns.append(n * c / self._width)
+        return Splines(columns)
+
+def build_spline_given_ends(x0, y0, slope0, x1, y1, slope1):
+    width = x1 - x0
+    slope0 = slope0 * width
+    slope1 = slope1 * width
+    a0 = y0
+    a1 = slope0
+    a2 = -2*slope0 - slope1 - 3*y0 + 3*y1
+    a3 = slope0 + slope1 + 2*y0 - 2*y1
+    return x0, x1, a3, a2, a1, a0