From: Stefano Zampini <stefano.zampini@gmail.com>
Date: Sat, 26 Nov 2022 18:42:31 +0000 (+0300)
Subject: STEP-77: fix bug
X-Git-Tag: v9.5.0-rc1~757^2~2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e09310ce5ceeefbe5608168baa27fe2f3a05520c;p=dealii.git

STEP-77: fix bug
---

diff --git a/examples/step-77/step-77.cc b/examples/step-77/step-77.cc
index 3f8a5bc379..ff6cfb319d 100644
--- a/examples/step-77/step-77.cc
+++ b/examples/step-77/step-77.cc
@@ -364,7 +364,7 @@ namespace Step77
                                     evaluation_point_gradients[q]);
 
             for (unsigned int i = 0; i < dofs_per_cell; ++i)
-              cell_residual(i) =
+              cell_residual(i) +=
                 (fe_values.shape_grad(i, q)      // \nabla \phi_i
                  * coeff                         // * a_n
                  * evaluation_point_gradients[q] // * \nabla u_n