implement math.comb ourselves

brunobeltran · brunobeltran · commit e2a5dc10faab · 2020-03-20T10:48:47.000-07:00
diff --git a/lib/matplotlib/bezier.py b/lib/matplotlib/bezier.py
@@ -9,7 +9,12 @@
 
 import matplotlib.cbook as cbook
 
-_comb = np.vectorize(math.comb)
+# same algorithm as 3.8's math.comb
+def _comb(n, k):
+    k = min(k, n - k)
+    i = np.arange(1, k + 1)
+    return np.prod((n + 1 - i)/i).astype(int)
+_comb = np.vectorize(_comb)
 
 class NonIntersectingPathException(ValueError):
     pass
@@ -277,6 +282,7 @@ def polynomial_coefficients(self):
 
         """
         n = self.degree
+        # matplotlib uses n <= 4. overflow plausible starting around n = 15.
         if n > 10:
             warnings.warn("Polynomial coefficients formula unstable for high "
                           "order Bezier curves!", RuntimeWarning)
