From 9a8c7e53250f918fb678509ed94622b350329fc9 Mon Sep 17 00:00:00 2001
From: Vighnesh Birodkar <vighneshbirodkar@gmail.com>
Date: Wed, 26 Nov 2014 23:10:49 +0530
Subject: [PATCH] fixed blob area overlap function warning

---
 skimage/feature/blob.py | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/skimage/feature/blob.py b/skimage/feature/blob.py
index 6431ed90..b13cad5d 100644
--- a/skimage/feature/blob.py
+++ b/skimage/feature/blob.py
@@ -53,8 +53,14 @@ def _blob_overlap(blob1, blob2):
     if d <= abs(r1 - r2):
         return 1
 
-    acos1 = arccos((d ** 2 + r1 ** 2 - r2 ** 2) / (2 * d * r1))
-    acos2 = arccos((d ** 2 + r2 ** 2 - r1 ** 2) / (2 * d * r2))
+    ratio1 = (d ** 2 + r1 ** 2 - r2 ** 2) / (2 * d * r1)
+    ratio1 = np.clip(ratio1, -1, 1)
+    acos1 = arccos(ratio1)
+
+    ratio2 = (d ** 2 + r2 ** 2 - r1 ** 2) / (2 * d * r2)
+    ratio2 = np.clip(ratio2, -1, 1)
+    acos2 = arccos(ratio2)
+
     a = -d + r2 + r1
     b = d - r2 + r1
     c = d + r2 - r1