I don't think that we have exactly what you want yet, but there is a
lot of infrastructure present to support it. Recently a tensor module
was added, and currently includes some support for differential forms,
for example:
x, y, z = var('x, y, z')
U = CoordinatePatch((x, y, z))
F = DifferentialForms(U)
form1 = DifferentialForm(F, 1)
form1[0] = x
form1[1] = z
form1[2] = y
form2 = DifferentialForm(F, 1)
form2[0] = 1
form2[1] = x
form2[2] = y
form2.wedge(form1)
works, returning an 2-form with string representation:
(x*y - y*z)*dy/\dz + (-x^2 + z)*dx/\dy + (-x*y + y)*dx/\dz
The maturing category framework in Sage should enable a nice
implementation of tensors. But apart from the continuing work on
differential geometry I am not sure anyone is specifically working on
that.
-Marshall Hampton
On Jan 12, 12:15 pm, Dmitry Shkirmanov <[email protected]> wrote:
> Hello, i need the object, that can be called by indication of his
> indeces, and number of this indeces is more than 2. For example in
> Sage there is class vector:
> #
> v=vector([a,b,c])
> #
> where a,b,c are sumbols.
> One can call element of this vector by
> #
> v[i]
> #
> where i=0,1,2.
> Also exist class matrix:
> #
> m=matrix([[a,b,c],[d,e,f]])
> #
> One can call element of this matrix by
> #
> m[i,j]
> #
> Now question:
> is there class, element of which can be called by indication of his
> indeces, but number of this indices is more than 2, i.e. something
> like t[i,j,k], t[i,j,k,l] ?
> I searched such class through the google and reference manual, but
> have not found it. Thanks for help.
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