Thank you so much for the clarification!<div><br></div><div>Sincerely,</div><div>Jay<br><br>On Wednesday, 11 November 2020, Erik Schnetter <<a href="mailto:schnetter@cct.lsu.edu">schnetter@cct.lsu.edu</a>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Jay<br>
<br>
This intermediate step comes from the time integrator. The Einstein<br>
Toolkit usually uses Runge-Kutta type time integrators that perform<br>
multiple sub-steps for each time step. These time integrators are<br>
provided by the "Methods of Lines" thorn ("MoL"). The respective<br>
documentation should have further pointers, and the respective<br>
parameter settings should also tell you more. (See also e.g.<br>
<<a href="https://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods" target="_blank">https://en.wikipedia.org/<wbr>wiki/Runge–Kutta_methods</a>>).<br>
<br>
-erik<br>
<br>
On Tue, Nov 10, 2020 at 12:20 PM Jay Vijay Kalinani<br>
<<a href="mailto:jayvijay.kalinani@phd.unipd.it">jayvijay.kalinani@phd.unipd.<wbr>it</a>> wrote:<br>
><br>
> Dear all,<br>
><br>
> I am trying to perform a magnetised TOV simulation using Einstein Toolkit and Spritz GRMHD code. In particular, currently I have a subroutine that adds a dipolar magnetic field to the TOV star after its initial data has been generated via TOVSolver thorn.<br>
> Within this subroutine, I have added the following lines that print the 'cctk_time' value as:<br>
><br>
> character(len=200) warnline<br>
> WRITE( warnline, '( "cctk_time: ", g16.7)' ) cctk_time<br>
> call CCTK_INFO(warnline)<br>
><br>
> This subroutine is scheduled in HydroBase_Con2Prim after Con2Prim step. And I get the following lines in the .out file as:<br>
> .........<br>
><br>
> INFO (TOVSolver): Integrated TOV equation<br>
><br>
> INFO (TOVSolver): Information about the TOVs used:<br>
><br>
> INFO (): TOV radius mass bary_mass mass(g) cent.rho rho(cgi) K K(cgi) Gamma<br>
><br>
> INFO (): 1 8.12502 1.40016 1.50618 2.78e+33 0.00128 7.92e+14 100 1.45e+05 2<br>
><br>
> INFO (TOVSolver): Not using old matter initial data<br>
><br>
> INFO (TOVSolver): Done interpolation.<br>
><br>
> INFO (Spritz_DipoleAndAtmo): cctk_time: 0.000000<br>
><br>
> INFO (Spritz_DipoleAndAtmo): Adding a poloidal magnetic field to the TOV star on reflevel 0<br>
><br>
> INFO (Spritz_DipoleAndAtmo): Adding atmo to the TOV star on reflevel = '0'<br>
><br>
> INFO (Spritz_DipoleAndAtmo): cctk_time: 0.000000<br>
><br>
> ------------------------------<wbr>------------------------------<wbr>------------------------------<wbr>------------------------------<wbr>-----------<br>
><br>
> Iteration Time | ADMBASE::alp | HYDROBASE::rho | HYDROBASE::press | SPRITZ::B_norm<br>
><br>
> | minimum maximum | minimum maximum | minimum maximum | minimum maximum<br>
><br>
> ------------------------------<wbr>------------------------------<wbr>------------------------------<wbr>------------------------------<wbr>-----------<br>
><br>
> 0 0.000 | 0.6698612 0.9603815 | 5.827798e-11 0.0012800 | 0.0000000 0.0001638 | 8.399814e-09 0.0000399<br>
><br>
> INFO (Spritz_DipoleAndAtmo): cctk_time: 0.3906250E-01<br>
><br>
> INFO (Spritz_DipoleAndAtmo): cctk_time: 0.3906250E-01<br>
><br>
> INFO (Spritz_DipoleAndAtmo): cctk_time: 0.7812500E-01<br>
><br>
> INFO (Spritz_DipoleAndAtmo): cctk_time: 0.7812500E-01<br>
><br>
> 1 0.078 | 0.6698612 0.9603833 | 5.827814e-11 0.0012799 | 0.0000000 0.0001638 | 8.294987e-09 0.0000395<br>
><br>
> INFO (Spritz_DipoleAndAtmo): cctk_time: 0.1171875<br>
><br>
> INFO (Spritz_DipoleAndAtmo): cctk_time: 0.1171875<br>
><br>
> INFO (Spritz_DipoleAndAtmo): cctk_time: 0.1562500<br>
><br>
> INFO (Spritz_DipoleAndAtmo): cctk_time: 0.1562500<br>
><br>
> 2 0.156 | 0.6698612 0.9603850 | 5.827829e-11 0.0012797 | 0.0000000 0.0001638 | 8.294994e-09 0.0000390<br>
><br>
> ..........<br>
><br>
><br>
><br>
><br>
> The simulation is performed in uniform grid with dx=dy=dz=0.3125, time::dtfac = 0.25 and HydroBase::timelevels = 2.<br>
> As you may see from the output lines, in between iteration 0 which is at cctk_time=0.0 and iteration 1 which is at cctk_time=0.078125, there is an intermediate time step with 'cctk_time=0.0390625' when the subroutine is called.<br>
><br>
> I was hoping to understand better why this intermediate time step exists between two consecutive iterations, and if there is any documentation I could look at.<br>
> Any help would be much appreciated.<br>
><br>
> Thank you very much.<br>
> Sincerely,<br>
> Jay Kalinani<br>
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<br>
<br>
<br>
-- <br>
Erik Schnetter <<a href="mailto:schnetter@cct.lsu.edu">schnetter@cct.lsu.edu</a>><br>
<a href="http://www.perimeterinstitute.ca/personal/eschnetter/" target="_blank">http://www.perimeterinstitute.<wbr>ca/personal/eschnetter/</a><br>
</blockquote></div>