step-15: doc update

diff --git a/examples/step-15/doc/results.dox b/examples/step-15/doc/results.dox
index 3fefe249fee6fcee62b1cc8e6debeb21413a872f..9aa5f0c173e17033370c8eea528e891a6ca960c7 100644 (file)
--- a/examples/step-15/doc/results.dox
+++ b/examples/step-15/doc/results.dox
@@ -137,7 +137,7 @@ Wolfe and Armijo-Goldstein conditions. For these, one can show the following:
   satisfied, i.e., the iteration never gets stuck as long as the problem is
   convex.
 - If we are close enough to the solution, then the conditions allow for
-  $\alpha^n$, thereby enabling quadratic convergence.
+  $\alpha^n=1$, thereby enabling quadratic convergence.
 
 We will not dwell on this here any further but leave the implementation of
 such algorithms as an exercise. We note, however, that when implemented
@@ -146,6 +146,9 @@ problems can be solved in anywhere between 5 and 15 Newton iterations to
 engineering accuracy — substantially fewer than we need with the current
 version of the program.
 
+More details on globalization methods including backtracking can be found,
+for example, in Griva, Nash, Sofer: Linear and nonlinear optimization (2009).
+
 
 <h4> Integrating mesh refinement and nonlinear and linear solvers </h4>