Correct typo in step-18 intro.dox

diff --git a/examples/step-18/doc/intro.dox b/examples/step-18/doc/intro.dox
index 784da5caf569271a345db801b26f81658d8292c3..91df0426b44935329ced4ada3046ce376cf28283 100644 (file)
--- a/examples/step-18/doc/intro.dox
+++ b/examples/step-18/doc/intro.dox
@@ -212,7 +212,7 @@ these equations can be simplified to
   &=
   (\mathbf{f}, \varphi)_{\Omega(t_{n-1})}
   -(\sigma^{n-1},\varepsilon(\varphi))_{\Omega(t_{n-1})}
-  +(\mathbf{b}(\mathbf{x},t_n),t_{n-1}), \varphi)_{\Gamma_N}
+  +(\mathbf{b}(\mathbf{x},t_n), \varphi)_{\Gamma_N}
   \\
   &\qquad\qquad
   \forall \varphi \in \{\mathbf{v}\in H^1(\Omega(t_{n-1}))^d: \mathbf{v}|_{\Gamma_D}=0\}.