On Saturday, November 23, 2013 2:04:35 AM UTC+1, Gilbert Gede wrote:
>
> In physics.mechanics, I actually tried to side-step this entire problem,
> by just using .x, .y, and .z for the three directions. We also allowed for
> users to define a custom string for an index, and access that direction via
> a dictionary using the index they defined (['1'], ['2'], ['3'], or ['i'],
> ['j'], ['k'], etc). But yeah, as Aaron said, we only had three dimensions.
> I don't know if that solution will be of any use to you.
>
For more options, visit https://groups.google.com/groups/opt_out.
>
>
The nice thing of the tensor module is abstract index notation. It is now
possible to store data into tensors and use a mixed abstract and numeric
convention to access data.
>>> LorentzIndex = TensorIndexType('Lorentz', dim=4)
>>> LorentzIndex.data = [1, -1, -1, -1] # the metric
>>> EuclideanIndex3D = TensorIndexType('E3D', dim=3)
>>> EuclideanIndex3D.data = [1, 1, 1]
My idea: whenever a tensor has a Lorentz index, it can also accept an
euclidean index on that slot. Passing an euclidean index strips the tensor
of the time-like coordinates on that index position. The problem is that by
doing so, the original data get shifted by 1, this problem could be avoided
by setting the offset of *EuclideanIndex3D* to one, something like this:
>>> EuclideanIndex3D = TensorIndexType('E3D', dim=3, offset=1)
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