## Arrangement of indices after Simplify...

After using Simplify the indices are are arranged in the tensor.  I am using the April 14th update from the Physics R&D page.

 (1)

 (2)

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 (4)

 (5)

We first define the Christoffel symbol in terms of the metric,   .

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Now we can substitute into the null condition for the Ricci tensor, .

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Do the first term

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Do same thing with the first term but use the Simplify command

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Simplify command does make the algebra easier, but the indices are not the same. Now, equation 16 should correspond to equation 14, but there is no combination of alphas that is consistent.  The variables alpha1 and alpha5 must be rho. One term is always wrong when I try to change the other indices.

alpha2 and alpha3 must be either mu or nu based on the first term.  But alpha6 should also be either mu or nu based on the last term, however that will make alpha2 and alpha3 either (nu and rho) or (mu and rho).  Neither combination makes all of the terms consistent with (14).  Very frustrating.

 (17)

## Advice sought on making input to a 3-d printer usi...

I have just begun thinking of trying to make some mathematically defined objects using a 3d printer. I would be happy to hear from anyone who has done this using Maple to prepare input. Pointers for a novice in 3d printing would be appreciated.  I have access to a MakerBot Replicator 2. But the people who have it have only used it to scan objects and make 3d copies of them.

---Edwin

## Error, (in dsolve/numeric/bvp/convertsys) too few ...

im solving 4 ODe with boundary conditions.. i got this error Error, (in dsolve/numeric/bvp/convertsys) too few boundary conditions: expected 8, got 7

## WHERE CAN I FIND CLICKABLE PHYSICS CLASSES IN ENGL...

You have clickable calc. Today I saw in your email that you have clickable physic but in french. Do you have it in english too>?

Thank you

manolo

## mtaylor expanssion...

Hello,

I have this expression on image below and I would like to do multi taylor in these variables. The maple says that the expansion is not possible to do. Does somebody know where the problem could be ? Thank you very much for help.

Equation:

Taylor series:

## How to plot a graph...

i solve 4 ODE with boundary condition.. i try to plot a graph F(eta) with different value of M.. but it doesnt comeout.. anyone can help me please??

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## I am so close to plot what I need but......

Hi everybody,

In quantum mechanics, I want to draw the wave  of the electron in the hydrogen atom.  So in 3D, you will have a cricle and along the circle, there will be a cosine function that will meet after a full cercle (the standing wave that is possible).  The blue one and the red one at the same time.  But in 3D

The closest that I come to succes is with this commands:

But as you will see, the wave end at the same place as it started.  But instead of going in a cercle, is as a funny shape.

Thank you in advance for you trouble.

--------------------------------------
Mario Lemelin
Maple 18 Ubuntu 13.10 - 64 bitsMaple 18 Win 7 -  64 bits
messagerie : mario.lemelin@cgocable.ca
téléphone :  (819) 376-0987

## Components of speed and acceleration.

Maple 18

With the package VectorCalculus we can study the speed and acceleration to their respective components. Considering the visualizaccion and algebraic calculations and to check with their respective commands. Both 2D and 3D.

Lenin Araujo Castillo

Physics Pure

Computer Science

## An integral that cause probel with Maple...

Hi Everybody.

Doing some calculation in quantum mechanics, I stuble on that integral:

I see immediately that the answer is 1/2.  But Maple 18 cannot give an answer other than a limit that he cannot evaluate.  I even try assumption that p and hbar are realcons.  I get infinity.

Any idea?

--------------------------------------
Mario Lemelin
Maple 18 Ubuntu 13.10 - 64 bitsMaple 18 Win 7 -  64 bits
messagerie : mario.lemelin@cgocable.ca
téléphone :  (819) 376-0987

## Matrix and parallel computing / multicore...

Hi,

Is there any difference between

Matrix(4,5,(K,C)->K+C);

and

Array(1..4,1..5,(K,C)->K+C);

Say if I have a very 'complicated' procedure myfunc(K,C) that takes two options, but it runs all dependently.

Matrix(4,5,(K,C)->myfunc(K,C));

and

Array(1..4,1..5,(K,C)->myfunc(K,C));

Which one is more efficient? The final ouput of each run from myfunc is just a integer value.

The reason I am asking it that i think both runs on a 'single' thread (core) as CPU usage is always very low, around 15-20%.

If I look at the task manager, some cores (threads) arent doing anything.

Is there anyway to speed things up?

Thanks,

by: Maple 18

## Getting a value of a constant...

Hello everybody,

While doing a document about quantum mechanics, I stumble on this strange behaviour.

>with(ScientificConstants);
>GetConstant();
>GetValue()

Error message:

Error, (in ScientificConstants:-GetValue) a[0] is not a scientific constant object

But in the Assistant Scientific Constant, the value is there: 5.291772e-11m

Why is it not directly available like I did the first time?

--------------------------------------
Mario Lemelin
Maple 18 Ubuntu 13.10 - 64 bitsMaple 18 Win 7 -  64 bits
messagerie : mario.lemelin@cgocable.ca
téléphone :  (819) 376-0987

## Division of maple worksheet...

Hello,

I would like to ask if one can divide the maple worksheet (mw) to multiple files like series of command. It could be simillar to include in C++. I have found only save and read command but they can be use only for variables or they can be use in other way ?

Thank you for any possible solution,

vidocq

## cat a subscript also as an input from a function...

f:=C->sum(x[cat(new,c)],c=1..C);

f(4) # does not give me what i want , which is

x[cat(new,1)]+x[cat(new,2)]+x[cat(new,3)]+x[cat(new,4)];

seq(x[cat(new,c)],c=1..4);
convert([%],+);

This works. But it's just a simple example to illustrate my problem.

Is there a way to fix this 'cat' problem in the procedure 'f'?

Thanks,

casper

## A tiny latex (from Maple) superscripts problem...

v1:=[seq(tau[lambda,i]^2,i=1..5)];

latex(v1);

gives:

[{\tau_{{\lambda,1}}}^{2},{\tau_{{\lambda,2}}}^{2},{\tau_{{\lambda,3}}
}^{2},{\tau_{{\lambda,4}}}^{2},{\tau_{{\lambda,5}}}^{2}]

which produces a non natural output in latex, see below.

I wonder it could be improved in the future release?

'latex' command is really useful when i have large algebric output. But having to change this tiny thing at many places is just very time consuming. I'd really appreciate if this can be fixed in updates or future versions of Maple.

Casper

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