@ecterrab 

Respected sir/madam
I wants to calculate the extrinsic curvature for a metric using maple but i don't know how to do it. Kindly help me out, how should I calculate the extrinsic curvature of a metric.
regards,
Suresh

@Markiyan Hirnyk 

i want to make plot and calculation of  the Appell function. but there are no commands for appell function. can I use hypergeom for Appell function? should i use hypergeom or there are any other way to figure this out?

Regards
Suresh

@ecterrab 

thanks for your help. i did got the Weyl Scalar and Ricci Scalar. However, the main problem is that i am not getting the results as shown by the author. it might be that, i may be missing something. But as per my knowledge i am appling the right formalism, as explained by you. i need to work it out. 

would do me a favour, do you have any idea about the debever formalism in tensor package. i am not able to understand there the defination of 'h'. just wana to check if he (author) is right, by finding the Weyl Scalars as stated by him.

thanks
suresh

@ecterrab 

i have given the metric in the attached file Weyl.mw. 

May be i am not able to tell you what exactly m looking for. Here, i have attached some info about my query. In this the author started from a general spherically symmetric metric(+---) and by using Newman-Janis algorithm he obtained finally the metric (22). Now he is making the statement that by using null tetrad in debever formalism in maple he got the weyl scalars, however i am not able to reproduce these results and same for the Ricci scalar. 

Thats what i was looking for and using physics package its not reproducing these results.

@ecterrab

nulltetrad.mw 

@ecterrab 

yes, it does work for metrics given in packages. i wondor if there is something wrong with my metric or something else. i have tried to find Weyl Scalar from nulltetrad using grtensor package, it does shows result for some of the scalars but results were not elegant and also it shows some kinda groptiondisplaylimit exceed error. was thinking to shift to physics package but here also the it is not showing the expected results(may be i am missing something or else)

thanks
suresh

@ecterrab 

Thanks,

It is really helpful. I was using grtensor package earlier to this but now i have feeling that physics package is much more advanced and simpler than grtensor. was intersted in finding Weyl scalars for a given metric, would be really helpful if u can give me a example of how to find a Weyl Scalar for a given metric or set of null tetrads using physics package.

Regards,

Suresh

@ecterrab 

hello dear,
Indead, physics package in maple is much more powerful and better than grtensor II. However, grtensorII gives you the freedom of adding your own metric, null tetrad and carry on the calculations etc. However, i am unaware if this freedom is  available to the user in physics package.

I would like to know that can we add metric/null tetrad manually in the physics package? or we can only use the metrics given in the physics package? and also how can we find out the list of the metrices available in physics package, so that we can find out if the metric, on which one is working on, is already available in the package or not?

Regards,
suresh

@Markiyan Hirnyk

yes, i did. i have metric and its null tetrad. there are two ways to find WeylScalar for a metric,as per my knowledge, either by this debever formalism or by using grtensor in maple. 
In the Debever formalism, i am not getting how to define this h, in general, for a given metric. and in the grtensor it is  showing 

Weyl Scalar, NP Psi2
Psi2 = 24364 words. Exceeds grOptionDisplayLimit
Weyl Scalar, NP Psi3
Psi3 = 7294 words. Exceeds grOptionDisplayLimit
Weyl Scalar, NP Psi4
Psi4 = 16947 words. Exceeds grOptionDisplayLimit

grtensor is working fine for the normal metric or for metric given in the grlib, however the kind of metric i am working its quaite complicated and it is showing this error.
so in both ways i  am not able to get WeylScalar

@Carl Love 

yes, it is Tensor package. it should be Debever's formalism using Tensor package. 
I had gone through the help and tried to solve the example given in the help for plane wave, howver, i am not able to find out how to define h for a given metric, as i have tried different ways like covarian contra product but results were not the same. i was looking if anyone has any idea about how to define this h in general for a given metric?

thanks
suresh