# [Users] weyl scalar symmetries

Yosef Zlochower yosef at astro.rit.edu
Fri May 18 15:04:48 CDT 2012

```On 05/18/2012 03:48 PM, Barry Wardell wrote:
> Hi Yosef,
>
> I'm not so familiar with the parities in the symmetry thorns, but I am
> reasonably confident that the manual Cartesian parities which are set by
> WeylScal4 are correct (in fact, there was correction committed just a
> few days ago).

The symmetries for WeylScal4 match the expected symmetries of the Weyl
scalars.

> So, it seems likely that the parities in the symmetry
> thorns are either wrong or my interpretation of what they mean is wrong.
>
> Can someone who is familiar with the symmetry thorns comment on whether
> the code there is correct? Are these parities used by any actively used
>

I have an old version of PsiKadelia, and the symmetries there seem
to be set incorrectly.

> Barry
>
> On Fri, May 18, 2012 at 4:02 PM, Yosef Zlochower <yosef at astro.rit.edu
> <mailto:yosef at astro.rit.edu>> wrote:
>
>     Hi,
>
>       I noticed that WeylScal4 sets the symmetries of the Weyl scalars by
>     defining the real and imaginary parts of each of the psi's in a
>     different group. RotatingSymmetry and the ReflectionSymmetry thorns
>     define a tensor alias "weylscalars_real", but the symmetries given there
>     do not correspond to those of the psi's.
>
>
>     The Weyl symmetries as provided in RotatingSymmetry180
>
>     static int const weylparities[10][3] =
>                {{+1,+1,+1},
>                 {-1,-1,-1},
>                 {+1,+1,+1},
>                 {-1,-1,-1},
>                 {+1,+1,+1},
>                 {-1,-1,-1},
>                 {+1,+1,+1},
>                 {-1,-1,-1},
>                 {+1,+1,+1},
>                 {-1,-1,-1}};
>
>
>     The symmetries for rpsi0, ipsi0, rpsi1, ipsi1, ..., rpsi4, ipsi4
>
>     static int const weylparities[10][3] =
>        {{+1,+1,+1},  /* rpsi0 */
>         {-1,-1,-1},  /* ipsi0 */
>         {+1,+1,-1},  /* rpsi1 */
>         {-1,-1,+1},  /* ipsi1 */
>         {+1,+1,+1},  /* rpsi2 */
>         {-1,-1,-1},  /* ipsi2 */
>         {+1,+1,-1},  /* rpsi3 */
>         {-1,-1,+1},  /* ipsi3 */
>         {+1,+1,+1},  /* rpsi4 */
>         {-1,-1,-1}}; /* ipsi4 */
>
>
>     --
>     Dr. Yosef Zlochower
>     Center for Computational Relativity and Gravitation
>     Assistant Professor
>     School of Mathematical Sciences
>     Rochester Institute of Technology
>     85 Lomb Memorial Drive
>     Rochester, NY 14623
>
>     Office:74-2067
>     Phone: +1 585-475-6103 <tel:%2B1%20585-475-6103>
>
>     yosef at astro.rit.edu <mailto:yosef at astro.rit.edu>
>
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--
Dr. Yosef Zlochower
Center for Computational Relativity and Gravitation
Assistant Professor
School of Mathematical Sciences
Rochester Institute of Technology
85 Lomb Memorial Drive
Rochester, NY 14623

Office:74-2067
Phone: +1 585-475-6103

yosef at astro.rit.edu

CONFIDENTIALITY NOTE: The information transmitted, including
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