What's in your differential geometry toolbox?

In summary: If there are some commands that you are entering manually every time, like "grtw():", you can add those commands to the end of the maple.ini file and they will automatically execute when you start Maple, or execute the "restart:" command.
  • #1
Aether
Gold Member
714
2
I saw GRTensorII mentioned here awhile back. What are the most powerful tools out there (which still run on a PC), including user manuals and texts, that you would recommend for working with field equations, curvature tensors, line elements, etc?
 
Physics news on Phys.org
  • #2
I bought a copy of Maple 10, and am now trying to install GRTensorII. If there is anyone here who has already done this, could you please tell me exactly how you installed the library and .ini files?
 
  • #3
I have an old moldy version of maple, and not Maple 10. I never got the ini files to run automatically, I always had to run them manually, or paste them into a document when I ran GRTensor.

I also added a line to redefine the Christoffel symbols to my ini file:

grdef(`CC{ ^a b c} := Chr{b c ^a}`);

By calculating CC(up,dn,dn), I get the Christoffel symbols in the format most textbooks use, rather than the peculiar format GRTensorII uses.
 
  • #4
Thanks pervect.

I found a way to get the ini file to run automatically. Maple only executes the first .ini file that it finds in a subdirectory, so if you place a maple.ini file in the bin.win (or bin.wnt) subdirectory as instructed it won't execute because there is already a launch.ini file in that subdirectory.

The solution is to place the maple.ini file in the LIB subdirectory, and then it will execute on Maple startup.

My GRTensorII is now up and running with your suggested addition. However, it isn't loading libraries (such as basislib.m) automatically as it should.
 
  • #5
Aether, I am exactly at that point where I figured I had to put the maple.ini file in the LIB directory so it works but Maple complains it can't find basislib.m although it's there.

Have you found a solution for basislib.m?
 
  • #6
smallphi said:
Aether, I am exactly at that point where I figured I had to put the maple.ini file in the LIB directory so it works but Maple complains it can't find basislib.m although it's there.

Have you found a solution for basislib.m?

I don't know if https://www.physicsforums.com/showpost.php?p=1241966&postcount=5" will help.
 
Last edited by a moderator:
  • #7
I put maple.ini in the Users directory of Maple.

basislib.m is probably the library of commands working with bases and still doesn't want to load. Everything else works as before.
 
  • #8
I've figured it out. The GRTensorII webpage says

With Maple 8 and 9, for the current release of GRTensorII, you need to load the libraries needed for your calculation. In previous versions of Maple they autoload. A typical initialization file is here. Simply download this file and follow the instructions in it. If you have developed your own libraries, load them in the same way.

You have to use the maple.ini file they are talking about because it contains commands to load all the libraries at startup. The ini file that comes with the GRTensor package loads only the library with the main commands grii.m.

Alternatively, you can use the old maple.ini file but load the libraries you need manually. The Maple command to load basislib.m is

readlib(basislib);

or you can use the GRTensor command

grlib(basislib);

After that everything works normal.
 
Last edited:
  • #9
Has anyone found a way in GRTensor to display functions without the arguments to cleanup the output. I have a long expression and I want the function X(r,t) to display as X. The aliases in GRTensor work only for derivatives but not for the functions.
 
  • #10
Check the path names in the maple.ini file to make sure that they are appropriate for where Grtii(6) is located on your hard drive, and put the maple.ini file in the Maple Users directory. Then start Maple and execute the commands "restart:" and then "grtw():" to get started.

If there are some commands that you are entering manually every time, like "grtw():", you can add those commands to the end of the maple.ini file and they will automatically execute when you start Maple, or execute the "restart:" command.

There are some sample worksheets in the "worksheets" folder of Grtii(6) where you can get some ideas about how to use the functions.
 
  • #11
Got this one too: use autoAlias if you want X(r,t) to be displayed as X.

The diffAlias creates aliases only for the partial derivatives not the function itself.
 
Last edited:
  • #12
I don't like how the autoAlias works in GRtensor. It substitutes X with X(r,t) everywhere so later if you need to calculate something like the particle derivative diff(X(r,t), r), you have to write that as diff(X, r).

A better implementation of aliasing is given by the declare command in the PDEtools package. Just write

with(PDEtools); declare(X(r,t));

and all derivatives of X(r,t) including the function itself will be displayed without the arguments at the same time diff(X(r,t), r) will work normal. I don't know how declare() is implemented but it seems it substitutes X(r,t) with X only in the output, without creating alias for X(r,t) -> X.
 
  • #13
Ok, sorry to raise a really old thread, but this has been annoying me all evening...

I've got GRTensor 1.79 working with Maple 10 quite happily; sorted out the ini files and loading of libraries and so on. My issue is when I type in "makeg(metricname);" it pastes some stuff to the screen but doesn't scroll it, and then pops up a message box and I don't know what I'm trying to enter. I much preferred the entry scheme in Maple 7 (what my old school had) where it prompted you to input the entry in the main window. Does anybody know how to get that form of entry working in Maple 10?

Thanks,
Jolyon
 

What is differential geometry?

Differential geometry is a branch of mathematics that studies the properties of curves and surfaces in higher dimensions. It combines concepts from calculus and linear algebra to understand the geometry of objects in spaces with varying curvature.

What is the purpose of a differential geometry toolbox?

A differential geometry toolbox is a collection of mathematical tools and techniques that are used to solve problems related to curves and surfaces in higher dimensions. It can be used to analyze and understand the behavior of objects in different types of spaces, such as Euclidean space, curved space, or abstract spaces.

What are some common applications of differential geometry?

Differential geometry has many practical applications in fields such as physics, engineering, computer graphics, and robotics. It is used to model and analyze the shape and movement of objects in the real world, such as the trajectory of a satellite, the design of a car body, or the motion of a robot arm.

What are some important concepts in differential geometry?

Some important concepts in differential geometry include curvature, geodesics, and differentiable manifolds. Curvature measures how much a surface deviates from being flat, geodesics are the shortest paths between two points on a curved surface, and differentiable manifolds are spaces that can be locally approximated by Euclidean space.

Do I need a strong background in mathematics to use a differential geometry toolbox?

While a strong foundation in mathematics, particularly in calculus and linear algebra, is helpful in using a differential geometry toolbox, it is not always necessary. Many software programs and packages have user-friendly interfaces that allow for the easy use of differential geometry techniques without extensive mathematical knowledge. However, a strong understanding of the underlying concepts is still important for solving complex problems and interpreting results accurately.

Similar threads

  • Special and General Relativity
Replies
20
Views
2K
  • Science and Math Textbooks
Replies
2
Views
2K
  • Special and General Relativity
Replies
5
Views
2K
  • Differential Geometry
3
Replies
70
Views
12K
  • Science and Math Textbooks
Replies
4
Views
1K
  • Special and General Relativity
Replies
31
Views
3K
  • STEM Academic Advising
Replies
3
Views
1K
  • STEM Academic Advising
Replies
8
Views
1K
  • STEM Academic Advising
Replies
17
Views
1K
  • Science and Math Textbooks
Replies
11
Views
2K
Back
Top