## 1490 Reputation

18 years, 161 days

```--------------------------------------
Mario Lemelin```
```Maple 14.00 Win 7 64 bits
Maple 14.00 Ubuntu 10,04 64 bitsmessagerie : mario.lemelin@cgocable.ca
téléphone :  (819) 376-0987```

## How to do symbolic calculation in GR...

Maple 2015

Hello everybody,

In the linearised theory of gravity, I want to do some symbolic calculations.  First, I need to set that:

Then I want to see how the Christoffel symbols will change by putting the above in this:

Any hint someone?  I really appreciate the help for learning the Physics package.  Thank you in advance.

Mario

## d'Alembertian in General Relativity don'...

Maple 2015

I have to prove the following:

So I do not need the explicit derivative of the function (r,t) . The metric is:

ds^2=(1-rg/r)*dt^2-(1-rg/r)^(-1)*dr^2

I am in the case of a collapsing star that emit radiation during the collapsing.  And I do not need to have a rotating black hole so that the reason I dont have dt*dr term in the metric, and I fix and .  So if you look in the Maple file attach to this post, I don't manage to obtain what I need to prove the equality between the two aspect of the same calculation.

Plese, take into account that I am sort of novice with the Physcis package and that the question is not part of an exam.

Mario Lemelin

dAlembertian.mw

## How to extract two sine waves in data?...

Maple

Hello everyone,

I have a set of data that I have imported in Maple.  When I plot the data, I can see that there are two sine waves in it.  It is a plot of radial velocity of a star versus time.  This is about a reflex motion of a star with an orbiting planet.  We will set that there is only one planet.

I would like to extract those two sine waves.  I am including that *.csv file that I imported in Maple that you can download at this address.

https://www.dropbox.com/s/4f4j5xm565je30x/Tyr_rv9_Maple.csv?dl=0

This is not for an exam but it is for a course in February and this will be very helpful and I want to share this file.  I can predict that there will be more than one planet but it is the idea that is important.

```--------------------------------------
Mario Lemelin```
```Maple 2015 Ubuntu 14.04 - 64 bitsMaple 2015 Win 10 Pro -  64 bits
messagerie : mario.lemelin@cgocable.ca
téléphone :  (819) 376-0987```

Maple 2015

Need help for manipulating tensor with the physics package.

I ask some questions about this.  But each time, I am refer to the help pages.  If I ask again some help, it is because I can't not start with the information on the help file.  It is written for people that already know General Relativity (GR).

So this time, I have created a document (attach to this post) where I ask specific queations on manipulations.  My goal is to ccrreate a document that I will put on the Applications Center.  I promess that those who will help me on this will be cited in the document.  This way, I hope to create an introduction on how to use tensors for beginner like me.

Then, with this help, I am sure I will be able to better understand the help page of the packages.  I am doing this as someone who is starting to learn GR and have to be able to better understand the manipulations of tensor and getting the grasp of teh meaning of all those tensor.  For exemple, the concept of parallel transport on a curve surface.

Thank you in advance for all the troubling I give you with this demand.

Regards,Parallel_Transport.mw

```--------------------------------------
Mario Lemelin```
```Maple 2015 Ubuntu 14.04 - 64 bitsMaple 2015 Win 7 -  64 bits
messagerie : mario.lemelin@cgocable.ca
téléphone :  (819) 376-0987```

## Finding contravariant bases vectors and ...

Maple

In preparation for learning GR, I need somme trick on how to use the DifferentialGEometry package or else. So I want to show you what I want to do (see the link to the document below) and I would like some help on how to do it with tensor.  That would help me a lot.  Then, I will extansion it on a 3-D problem and next in 4-D.

here is the file : Finding_covariant_and_contravariant.mw

```--------------------------------------
Mario Lemelin```
```Maple 2015 Ubuntu 14.04 - 64 bitsMaple 2015 Win 10 -  64 bits
messagerie : mario.lemelin@cgocable.ca
téléphone :  (819) 376-0987```
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