]> https://gitweb.dealii.org/ - dealii.git/commitdiff
Add a changelog entry.
authorWolfgang Bangerth <bangerth@colostate.edu>
Tue, 21 Jan 2025 22:17:58 +0000 (15:17 -0700)
committerWolfgang Bangerth <bangerth@colostate.edu>
Mon, 27 Jan 2025 20:28:25 +0000 (13:28 -0700)
doc/news/changes/incompatibilities/202501121Bangerth [new file with mode: 0644]

diff --git a/doc/news/changes/incompatibilities/202501121Bangerth b/doc/news/changes/incompatibilities/202501121Bangerth
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+Changed: The SolverControl, ReductionControl, and
+IterationNumberControl classes have constructors that take two boolean
+flags `log_history` and `log_result`. The first of these represents
+whether each time these classes are asked to evaluate progress of an
+iterative solver, it should output information about the current
+number of the iteration and the current residual to the `deallog`
+object. The latter flag determines whether this kind of output should
+be generated once the solver has been determined to have either
+succeeded or failed, i.e., at the end of the iteration. By default,
+these flags were set to `false` and `true`, respectively.
+
+Creating and formatting this kind of output turns out to be
+surprisingly expensive. This is a nuisance because by default, the
+`deallog` variable (via the constructor arguments of the LogStream
+class) is instructed to simply ignore whatever information is sent to
+it, rather than putting the output onto the screen or into a log file.
+
+As a consequence, the defaults of the constructor arguments of the
+three classes mentioned above have been changed from `false` and
+`true` to `false` and `false`. If you have instructed `deallog` to
+pass information given to it to the screen or into an output file, you
+can always explicitly also set the constructor arguments of
+SolverControl, ReductionControl, or IterationNumberControl objects to
+retain the previous behavior.
+<br>
+(Wolfgang Bangerth, 2025/01/21)

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