<html>#2487: *_evolution_method = "LeanBSSNMoL" in Lean does nothing
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<tr><td style='text-align:right'> Reporter:</td><td>Gabriele Bozzola</td></tr>
<tr><td style='text-align:right'> Status:</td><td>new</td></tr>
<tr><td style='text-align:right'>Milestone:</td><td></td></tr>
<tr><td style='text-align:right'> Version:</td><td>development version</td></tr>
<tr><td style='text-align:right'> Type:</td><td>bug</td></tr>
<tr><td style='text-align:right'> Priority:</td><td>major</td></tr>
<tr><td style='text-align:right'>Component:</td><td>EinsteinToolkit thorn</td></tr>
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<p>Comment (by Gabriele Bozzola):</p>
<p>The way I personally interpret the parameter <code>lapse_evolution_method</code> (and <code>shift_evolution_method</code>) is “the lapse will be evolved according to the method specified”. Therefore, my expectation is that that if it is not set to <code>LeanBSSNMoL</code> (or <code>ML_BSSN</code>), <code>Lean</code> (or <code>ML_BSSN</code>) should not evolve the lapse. In this way I can set it to <code>static</code> (evolve the metric in a fixed gauge, which is why I needed this), or develop my thorn to evolve with my personal choice. However, I don’t know if this is the intended behavior or not. Maybe <code>evolution_method</code> implies that metric, lapse, and shift have to be evolved in the same way.</p>
<p>In any case, it is easy trivial to implement the behavior I describe: the simplest way is to put a conditional in front of the code that writes <code>rhs_lapse</code> and <code>rhs_shift</code> checking if <code>lapse_evolution_method</code> is <code>LeanBSSNMoL</code>. A better solution should also avoid computing/syncing stuff that is not needed.</p>
<p>--<br/>
Ticket URL: <a href='https://bitbucket.org/einsteintoolkit/tickets/issues/2487/_evolution_method-leanbssnmol-in-lean-does'>https://bitbucket.org/einsteintoolkit/tickets/issues/2487/_evolution_method-leanbssnmol-in-lean-does</a></p>
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