Fix a typo in step-19

diff --git a/examples/step-19/doc/intro.dox b/examples/step-19/doc/intro.dox
index 58d33cbed7c6c8ad41f2985cf71a2bc3d3387d6e..f424f38b037a3753f0b4ae94945c199975c43a48 100644 (file)
--- a/examples/step-19/doc/intro.dox
+++ b/examples/step-19/doc/intro.dox
@@ -25,7 +25,7 @@ this simply leads to a set of ordinary differential equations, for example
 if you want to track the positions of the planets in the solar system over
 time, then deal.II is clearly not the right tool. On the other hand, if
 this evolution is due to the interaction with the solution of partial differential
-equation, or if having a mesh to determine which particles interact
+equations, or if having a mesh to determine which particles interact
 with others (such as in the
 [smoothed particle hydrodynamics (SPH)](https://en.wikipedia.org/wiki/Smoothed-particle_hydrodynamics)
 method), then deal.II has support for you.