Cleaned up _ppf_single after reviewer comment.

gwgundersen · Jul 18, 2020 · 80edda0 · 80edda0
1 parent 0e6a03f
commit 80edda0
Showing 1 changed file with 9 additions and 15 deletions.
diff --git a/scipy/stats/_distn_infrastructure.py b/scipy/stats/_distn_infrastructure.py
@@ -1655,26 +1655,20 @@ def _ppf_to_solve(self, x, q, *args):
         return self.cdf(*(x, )+args)-q
 
     def _ppf_single(self, q, *args):
-        left = right = None
-        _a, _b = self._get_support(*args)
-        if _a > -np.inf:
-            left = _a
-
         factor = 10.
-        if not left:  # i.e. self.a = -inf
-            left = -1.*factor
+        left, right = self._get_support(*args)
+
+        if np.isinf(left):
+            left = min(-factor, right)
             while self._ppf_to_solve(left, q, *args) > 0.:
-                right = left
-                left *= factor
+                left, right = left * factor, left
             # left is now such that cdf(left) < q
+            # if right has changed, then cdf(rught) >= q
 
-        if _b < np.inf:
-            right = _b
-        else:
-            right = factor
+        if np.isinf(right):
+            right = max(factor, left)
             while self._ppf_to_solve(right, q, *args) < 0.:
-                left = right
-                right *= factor
+                left, right = right, right * factor
             # right is now such that cdf(right) > q
 
         return optimize.brentq(self._ppf_to_solve,