From 8889a2c1c648f5dd1413dc2d94c2407c7ce1bd32 Mon Sep 17 00:00:00 2001
From: Forrest Voight <forrest@forre.st>
Date: Sat, 23 May 2020 19:00:02 -0500
Subject: [PATCH] Add operator==/operator!= to Quaternion. Fixes #1876.

---
 Eigen/src/Geometry/Quaternion.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/Eigen/src/Geometry/Quaternion.h b/Eigen/src/Geometry/Quaternion.h
index 7b2c4d89d..dd1217e5e 100644
--- a/Eigen/src/Geometry/Quaternion.h
+++ b/Eigen/src/Geometry/Quaternion.h
@@ -158,6 +158,22 @@ class QuaternionBase : public RotationBase<Derived, 3>
 
   template<class OtherDerived> EIGEN_DEVICE_FUNC Quaternion<Scalar> slerp(const Scalar& t, const QuaternionBase<OtherDerived>& other) const;
 
+  /** \returns true if each coefficients of \c *this and \a other are all exactly equal.
+    * \warning When using floating point scalar values you probably should rather use a
+    *          fuzzy comparison such as isApprox()
+    * \sa isApprox(), operator!= */
+  template<class OtherDerived>
+  EIGEN_DEVICE_FUNC inline bool operator==(const QuaternionBase<OtherDerived>& other) const
+  { return coeffs() == other.coeffs(); }
+
+  /** \returns true if at least one pair of coefficients of \c *this and \a other are not exactly equal to each other.
+    * \warning When using floating point scalar values you probably should rather use a
+    *          fuzzy comparison such as isApprox()
+    * \sa isApprox(), operator== */
+  template<class OtherDerived>
+  EIGEN_DEVICE_FUNC inline bool operator!=(const QuaternionBase<OtherDerived>& other) const
+  { return coeffs() != other.coeffs(); }
+
   /** \returns \c true if \c *this is approximately equal to \a other, within the precision
     * determined by \a prec.
     *