Re: [sympy] Finding the Riemann tensor for the surface of a sphere with sympy.diffgeom

It turns out that the Christoffel symbol of second kind found with sympy.diffgeom was invalid. I will try to make a new post here for this soon. On Saturday, October 24, 2015 at 9:11:28 PM UTC+2, Imran Ali wrote: > > I have made a geodesic solver using sympy.diffgeom and scipy.integrate. >

Re: [sympy] Finding the Riemann tensor for the surface of a sphere with sympy.diffgeom

I did not check the calculations, but... are you sure it's not a problem of valence (i.e. contravariant or covariant indices differ)? We need a tensor-array data structure (i.e. an N-dimensional array with valence markings) to solve this kind of confusion. On Monday, 26 October 2015 12:18:04

Re: [sympy] Finding the Riemann tensor for the surface of a sphere with sympy.diffgeom

I have made a geodesic solver using sympy.diffgeom and scipy.integrate. Currently I am having some issue with the solver. But the problem may be related to Scipy. I have posted a thread here :

Re: [sympy] Finding the Riemann tensor for the surface of a sphere with sympy.diffgeom

On Monday, 19 October 2015 19:32:22 UTC+2, Francesco Bonazzi wrote: > > We should eventually merge this: > https://github.com/sympy/sympy/pull/9112 > > Given that this PR is too large to review, I extracted and rewrote the code concerning N-dim arrays (made it more similar to SymPy's matrix

Re: [sympy] Finding the Riemann tensor for the surface of a sphere with sympy.diffgeom

On Saturday, October 17, 2015 at 8:49:28 PM UTC+2, Francesco Bonazzi wrote: > > > > On Saturday, 17 October 2015 17:52:38 UTC+2, Imran Ali wrote: > >> >> But this result does not correspond to the hand calculations of Thomas >> Moore : >> >> > Do you know that unlike matrices tensors don't have

Re: [sympy] Finding the Riemann tensor for the surface of a sphere with sympy.diffgeom

On Mon, Oct 19, 2015 at 7:59 AM, Imran Ali wrote: > > > On Saturday, October 17, 2015 at 8:49:28 PM UTC+2, Francesco Bonazzi wrote: >> >> >> >> On Saturday, 17 October 2015 17:52:38 UTC+2, Imran Ali wrote: >>> >>> >>> But this result does not correspond to the hand

Re: [sympy] Finding the Riemann tensor for the surface of a sphere with sympy.diffgeom

We should eventually merge this: https://github.com/sympy/sympy/pull/9112 The TensorArray object is a multi-dimensional array with valence markings. It could be linked to the differential geometry module, to replace lists of lists of lists of lists. On Monday, 19 October 2015 16:31:37 UTC+2,

Re: [sympy] Finding the Riemann tensor for the surface of a sphere with sympy.diffgeom

On Saturday, 17 October 2015 17:52:38 UTC+2, Imran Ali wrote: > > But this result does not correspond to the hand calculations of Thomas > Moore : > > Do you know that unlike matrices tensors don't have defined components? I mean, you may vary their valence (i.e. raise and lower the indices),

Re: [sympy] Finding the Riemann tensor for the surface of a sphere with sympy.diffgeom

Hi Ondrej. I implemented this case with sympy.diffgeom, but the results I get back are not what I expected them to be. I posted the implementation here : http://pastebin.com/k7UZ4PYy The Christoffel Riemann tensor the code calculates is as following : [[ [ [0, 0], [0, 0]], [ [0,

[sympy] Finding the Riemann tensor for the surface of a sphere with sympy.diffgeom

I have implemented a SymPy program that can calculate the Riemann curvature tensor for a given curve element. However, I am encountering problems solving for the case when the curve element is the surface of a sphere \begin{align} ds^2 = r^2d\theta^2 + r^2 \sin^2\theta d\phi^2 \end{align} This

Re: [sympy] Finding the Riemann tensor for the surface of a sphere with sympy.diffgeom

On Wed, Oct 14, 2015 at 3:25 PM, Ondřej Čertík wrote: > Hi Imran, > > On Wed, Oct 14, 2015 at 10:14 AM, Imran Ali wrote: >> I have implemented a SymPy program that can calculate the Riemann curvature >> tensor for a given curve element. However,

Re: [sympy] Finding the Riemann tensor for the surface of a sphere with sympy.diffgeom

Hi Imran, On Wed, Oct 14, 2015 at 10:14 AM, Imran Ali wrote: > I have implemented a SymPy program that can calculate the Riemann curvature > tensor for a given curve element. However, I am encountering problems > solving for the case when the curve element is the surface