From 49ba9a79907da70d11a4316ae1af8fc3f5b323a5 Mon Sep 17 00:00:00 2001
From: alexma3312 <alexma3312@gmail.com>
Date: Mon, 28 Sep 2020 20:52:31 -0400
Subject: [PATCH] Throw an exception when n=0 .

---
 gtsam/geometry/Point3.cpp | 1 +
 gtsam/geometry/Point3.h   | 1 +
 2 files changed, 2 insertions(+)

diff --git a/gtsam/geometry/Point3.cpp b/gtsam/geometry/Point3.cpp
index ce4ceee89..783741262 100644
--- a/gtsam/geometry/Point3.cpp
+++ b/gtsam/geometry/Point3.cpp
@@ -77,6 +77,7 @@ double dot(const Point3 &p, const Point3 &q, OptionalJacobian<1, 3> H1,
 
 Point3Pair mean(const std::vector<Point3Pair> &abPointPairs) {
   const size_t n = abPointPairs.size();
+  if (n == 0) throw std::invalid_argument("input should have at least 1 pair of points");
   Point3 aCentroid(0, 0, 0), bCentroid(0, 0, 0);
   for (const Point3Pair &abPair : abPointPairs) {
     aCentroid += abPair.first;
diff --git a/gtsam/geometry/Point3.h b/gtsam/geometry/Point3.h
index 7f58497e9..b400470ea 100644
--- a/gtsam/geometry/Point3.h
+++ b/gtsam/geometry/Point3.h
@@ -62,6 +62,7 @@ GTSAM_EXPORT double dot(const Point3& p, const Point3& q,
 /// mean
 template <class CONTAINER>
 GTSAM_EXPORT Point3 mean(const CONTAINER& points) {
+  if (points.size() == 0) throw std::invalid_argument("input should have at least 1 point");
   Point3 sum(0, 0, 0);
   sum = std::accumulate(points.begin(), points.end(), sum);
   return sum / points.size();