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Hello;

 

I wish to express a tensorial equation or expression a simplified vector form.

 

In the worksheet attached, I was trying to express Maxwell Equations in the familiar vector form from the tensorial form, using the F[mu,nu] tensor.

 

But I cannot achieve the familiar tensor form. If someone can give a hand, it would help me a lot.

 

HowtoExpressCompactForm.mw

 

 

how to generate random data from equations of electromagnetism?

Hi Edgardo/Others, 

I'm not sure if any more development work is being done on the physics package or not. But I've gotten back to playing around with the great tetrad package you've developed. 

Specfically, I'm calculating spin connections for various metrics. I've run into a few troubles, and have written a simple example showing some calculations that don't match my expectations. 

This is by no means urgent, and if you are no longer developing the package, you can ignore this post. 

Hopefully you can follow the code, I've commented on the issues I have, summary:

1. Checking the tetrads match the minkowski metric when contracted with the curved metric. 

2. I build a tensor Gamma_mu (represents spin connection for a covariant derivative) which contains non-commuting gamma matricies (ideally dirac gamma's). I then try and contract this tensor with another non commutating tensor (dirac gamma matrix) using SumOverRepeatedIndices(). Unless I'm mistaken, this function doesn't preserve the anticommuting nature of the tensor components. 

Cheers. 

Correcting_-_Tetrads.mw

r := sqrt(x^2+y^2+z^2);
divE := diff(e*x/(4*Pi*r^3), x)+diff(e*x/(4*Pi*r^3), y)+diff(e*x/(4*Pi*r^3),z);
simplify(divE);

Using with(Physics):

On an initial condition setting for using dsolve when I do D(theta)(0) it returns  0=0

I'll have to check tonight if it's a mistake on my part.  But perhaps that is supposed to happen.

guys , i have a metric and i want to define a componenets of a tensor and then obtain its covariant derivative with respect to a metric, what is your idea ?

N_1=-A(r)^1/2 , A_2=A_3=A_4=0 , what is D_[nu] N_1 =?

 in general i want to define N[1]=-A(r)^(1/2) and N[2] = N[3]= N[3] = N[4] = 0 And define F[mu, nu] = 2*(D_[mu] N[nu]-D_[nu] N[mu]) And define Omega[mu, nu] = 2*(D_[mu] N[nu]+D_[nu] N[mu]) and compute expression F_[alpha, beta] F_[~alpha`, ~beta ] And N_[alpha] N_[~beta`] F_[ ~alpha, ~lambda ] Omega_[beta, lambda])

i have problem with this how to difine this tensorial terms and how to compute them.

Covariant.mw

 

thxxxx

Some of the Rotation Coefficients are not calculating properly.

Question_about_Ricci_Rotation_Coefficients.mw

 

 

Hi!

 

I was trying to obtain the field equations for the QED Lagrangian and I was not sucessfull.

 

All my calculations are equal to 0.

 

Can someone give a hand?

 

QED.mw

 

Thanks a lot.

guys, is there any possibility to obtain field equations of einstein-hilbert action?

best regards

 

Dear all
I am using Physics[Vectors] package of Maple 17. I want to define an orthogonal curvilinear coordinates through alpha and beta independent variables. To define unit vectors of alpha and beta, I have to apply the derivatives of position vector r_ with respect to alpha and beta, respectively. Please help me to define the unit vectors in directions alpha and beta as derivatives of position vector r_ with respect to alpha and beta, respectively. Please see the below Code:


> restart;

> with(Physics[Vectors]);

> Setup(mathematicalnotation=true);

> r_:=X(alpha,beta)*_i+Y(alpha,beta)*_j+Z(alpha,beta)*_k;


The unit vectors in directions alpha and beta should be defined as:

_alpha=diff(r_,alpha)
_beta=diff(r_,beta)

It is worthwhile to mention that the following expression governs:


> diff(r_,alpha).diff(r_,beta)=0;

 

Please guide me.

Best wishes

Ali

with(Physics) :
t:=Intc(Dirac(k1+k2+k3)*phi(k1)*phi(k2)*phi(k3),k1,k2,k3) ;


# how to force
Fundiff(t,phi(-k));

# to find
3*Intc(Dirac(k2+k3-k)*phi(k2)*phi(k3),k2,k3) ;

 

The physics package is pretty awesome, but one thing that would be a big help is some functionality for entering and resolving vectors in angle/magnitude format (50 angle 45 degrees, or what have you.) Is there a way to do this?

 

Thanks

 

Joe

Hi guys, 

       After my calculations, I got the Lagrange function having three gereralized co-ordinates namely u,v and w. Hence, according to theory it should give three equations of motion. 

      I have trouble finding equations of motion from following Lagrange function(L = T -U), Can anyone guide me with this?

      Moreover, kinetic energy and strain energy equations are in the form of double integral!! 

 

 

Hello. I am engaged in independent study of tensor calculus (in the annex to the theory of elasticity) and package Maple. Currently engaged in the action of a solution of the normal point force on elastic half-space (Boussinesq problem, for example, see http://solidmechanics.org/Text/Chapter5_4/Chapter5_4.php#Sect5_4_4). The point is this: you need to create a vector displacement field U, differentiate and create a strain tensor, and then using Hooke's law to obtain the stress tensor. Actually only started to understand and immediately raised the question. Creating vector displacement field using the VectorField package VectorCalculus or any team or package DifferentialGeometry Physic? How then create a tensor with components equal to the partial derivatives of the displacement vector? My attempts Boussinesq_problem.mw. Thanks for your help.

1.   can not  define  equation  when not known  E

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