Clarify a comment in step-77.

diff --git a/examples/step-77/step-77.cc b/examples/step-77/step-77.cc
index 8376adf554402fa713762829df1c5480263112e9..174858b3109c9d768303a4c81e3b6a8ef095706d 100644 (file)
--- a/examples/step-77/step-77.cc
+++ b/examples/step-77/step-77.cc
@@ -77,7 +77,7 @@ namespace Step77
   // (If you are wondering why the program uses a direct object for the Jacobian
   // matrix but a pointer for the factorization: Every time KINSOL requests that
   // the Jacobian be updated, we can simply write `jacobian_matrix=0;` to reset
-  // it to an empty matrix that we can then fill again. On the other hand, the
+  // it to a zero matrix that we can then fill again. On the other hand, the
   // SparseDirectUMFPACK class does not have any way to throw away its content
   // or to replace it with a new factorization, and so we use a pointer: We just
   // throw away the whole object and create a new one whenever we have a new