<html>#2299: Proposal: Add BaikalETK to the Toolkit
<table style='border-spacing: 1ex 0pt; '>
<tr><td style='text-align:right'> Reporter:</td><td>Zach Etienne</td></tr>
<tr><td style='text-align:right'> Status:</td><td>open</td></tr>
<tr><td style='text-align:right'>Milestone:</td><td>ET_2020_05</td></tr>
<tr><td style='text-align:right'> Version:</td><td></td></tr>
<tr><td style='text-align:right'> Type:</td><td>enhancement</td></tr>
<tr><td style='text-align:right'> Priority:</td><td>major</td></tr>
<tr><td style='text-align:right'>Component:</td><td></td></tr>
</table>
<p>Comment (by helvi witek):</p>
<p>Adding my original report to Zach and our respective replies:</p>
<h2 id="markdown-header-report-on-baikal-and-baikalvacuum-4013-may-202041">Report on Baikal and BaikalVacuum (13 May 2020)</h2>
<ul>
<li>Two thorns "Baikal" (Einstein's equations coupled to Tmn) and "BaikalVacuum" (Einstein's equations in vacuum)</li>
<li>very clean and readable implementation, both the the jupyter notebook and the auto-generated code.</li>
<li>exceptionally well documented</li>
<li>benchmarked against McLachlan (and Lean test is underway): reproduces standard qc0 run (BBH with 1 orbit before merger)</li>
</ul>
<h2 id="markdown-header-baikal-4013-may-202041">Baikal (13 May 2020):</h2>
<ul>
<li>
<p>README:</p>
<ul>
<li>"...in parfile_examples/" should be "... in par/" to be consistent with source code structure</li>
</ul>
</li>
<li>
<p>interface.ccl</p>
<ul>
<li>definition of BSSN grid functions: you might consider using tags for the tensortype and tensorweight.<br />
(Q: how does it impact the evolution or is it only information?).<br />
Doing so would require to split the evolution variables into groups of same type and weight.</li>
</ul>
</li>
<li>
<p>param.ccl:</p>
<ul>
<li>[CHECK:] no floor_value for conformal factor or lapse -- how is the zero at the puncture treated?</li>
</ul>
</li>
<li>
<p>schedule.ccl:</p>
<ul>
<li>Why do you store the ADMBase gridfunctions (again) in Baikal? This is done in ADMBase/schedule.ccl, so why is it necessary here?</li>
<li>[CHECK:] BSSN-to-ADM conversion before calculating Ricci and rhs. Why?</li>
</ul>
</li>
<li>
<p>src/Symmetry_registration_oldCartGrid3D.c:</p>
<ul>
<li>[CORRECTION:] default symmetry setting is hardwired that of a scalar in every tensor component.<br />
This should be corrected, otherwise using symmetries to reduce run costs might yield incorrect results.<br />
For example, gammax has symmetry (-1,1,1).</li>
</ul>
</li>
<li>
<p>src/BSSN_to_ADM.c</p>
<ul>
<li>[CHECK:] trafo is $\gamma_{xx} = \frac{1}{cf^2} (\tilde{\gamma}_{xx}+1 )$ (why "+1"?) and same for yy and zz
<p>--<br/>
Ticket URL: <a href='https://bitbucket.org/einsteintoolkit/tickets/issues/2299/proposal-add-baikaletk-to-the-toolkit'>https://bitbucket.org/einsteintoolkit/tickets/issues/2299/proposal-add-baikaletk-to-the-toolkit</a></p>
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