I am just trying to add this spacetime, I dont want to use it in some other thorns of the toolkit. and I am not familiar with xAct package.
<https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon> Virus-free. www.avast.com <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> On Tue, Nov 7, 2017 at 8:31 PM, Ian Hinder <ian.hin...@aei.mpg.de> wrote: > > On 7 Nov 2017, at 14:04, Nisa Amir <nisaa...@math.qau.edu.pk> wrote: > > Yes, the mathematica package is given but it accepts the metric only in > cartesian coordinates. I want to add the spacetime non kerr which is in > polar coordinates to the mathematica package in Einstein Exact thorn. What > transformations should I made? > > > Hi, > > You can apply the usual basis transformations in Mathematica to generate > the metric in a quasi-Cartesian basis and coordinates. This will then > allow you to construct the spacetime numerically in these coordinates, and > the thorns in the toolkit which expect quasi-Cartesian coordinates will > just work, for example the horizon finder. You would then evolve in 3+1 > dimensions. I have done this for Kerr in Boyer-Lindquist coordinates using > the xAct tensor manipulation package. This is not straightforward, and > it's not something that I would take on lightly if you don't have much > experience with EinsteinExact or xAct. > > However, you have said that you want to store the gridfunctions in polar > coordinates, and do the evolution in polar coordinates. I have no > experience with this, and many of the thorns in the toolkit which expect > quasi-Cartesian coordinates will just not work (e.g. the horizon finder). > That is why I asked you what you are trying to do. Please can you answer > that, before we go into a lot of detail about how to do it in one > particular way, which may in the end not help you? > > Thanks! > > -- > Ian Hinder > http://members.aei.mpg.de/ianhin > >
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