From aeb8f77a470e991bea1d016526da9d587b29fda3 Mon Sep 17 00:00:00 2001
From: Andreas Dutzler <a.dutzler@gmail.com>
Date: Mon, 2 Sep 2024 22:53:24 +0200
Subject: [PATCH] Update _base.py

---
 src/felupe/field/_base.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/felupe/field/_base.py b/src/felupe/field/_base.py
index b28ecff9..39465b04 100644
--- a/src/felupe/field/_base.py
+++ b/src/felupe/field/_base.py
@@ -184,8 +184,10 @@ def hess(self, dtype=None, out=None):
 
         ..  math::
 
-            \left( \frac{\partial u_i}{\partial X_J} \right)_{(qc)} =
-                \hat{u}_{ai} \left( \frac{\partial h_a}{\partial X_J} \right)_{(qc)}
+            \left( \frac{\partial^2 u_i}{\partial X_J~\partial X_K} \right)_{(qc)} =
+                \hat{u}_{ai} \left(
+                    \frac{\partial^2 h_a}{\partial X_J~\partial X_K}
+                \right)_{(qc)}
 
         Parameters
         ----------