From 3a609351f75d20cdd946bc872aac4b1a4faa0b46 Mon Sep 17 00:00:00 2001
From: Wolfgang Bangerth <bangerth@colostate.edu>
Date: Wed, 19 Jan 2022 20:19:55 -0700
Subject: [PATCH] Update output.

---
 examples/step-3/doc/results.dox | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/examples/step-3/doc/results.dox b/examples/step-3/doc/results.dox
index ae8b6c9862..f03e517bd8 100644
--- a/examples/step-3/doc/results.dox
+++ b/examples/step-3/doc/results.dox
@@ -5,18 +5,21 @@ The output of the program looks as follows:
 Number of active cells: 1024
 Number of degrees of freedom: 1089
 DEAL:cg::Starting value 0.121094
-DEAL:cg::Convergence step 48 value 5.33692e-13
+DEAL:cg::Convergence step 36 value 7.07761e-08
 @endcode
 
-The first two lines is what we wrote to <code>cout</code>. The last
-two lines were generated without our intervention by the CG
-solver. The first two lines state the residual at the start of the
-iteration, while the last line tells us that the solver needed 47
-iterations to bring the norm of the residual to 5.3e-13, i.e. below
-the threshold 1e-12 which we have set in the `solve' function. We will
-show in the next program how to suppress this output, which is
-sometimes useful for debugging purposes, but often clutters up the
-screen display.
+The first two lines is what we wrote to <code>std::cout</code>. The last
+two lines were generated by the CG solver because we called
+`deallog.depth_console(2);` in the `main()` function -- see
+the lengthy discussion there. These two lines prefixed by `DEAL:cg:` state
+the residual at the start of the
+iteration and that the solver needed 36
+iterations to bring the norm of the residual to $7.08\cdot 10^{-8}$, i.e. below
+the threshold $\tau$ which we have set in the `solve()` function.
+Note that we have asked the residual to be less than $10^{-6}$ times the
+norm of the right hand side vector; the starting value is (here) this
+norm of the right hand side vector, and there is indeed more than a
+factor of $10^{-6}$ between the two values shown.
 
 Apart from the output shown above, the program generated the file
 <code>solution.vtk</code>, which is in the VTK format that is widely
-- 
2.39.5