<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><br><div><div>On 7 Nov 2017, at 14:04, Nisa Amir <<a href="mailto:nisaamir@math.qau.edu.pk">nisaamir@math.qau.edu.pk</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div dir="ltr">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?</div></blockquote><div><br></div><div>Hi,</div><div><br></div><div>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.</div><div><br></div><div>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?</div><div><br></div><div>Thanks!</div><div><br></div></div><div apple-content-edited="true">
<div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div>-- </div><div>Ian Hinder</div><div><a href="http://members.aei.mpg.de/ianhin">http://members.aei.mpg.de/ianhin</a></div></div></div></div></div>
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