Re: [GiNaC-list] How to differentiate from a Tensor?

14 Jul 2017

      On 7/14/17, Vladimir V. Kisil <kisilv@maths.leeds.ac.uk> wrote:
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On Fri, 14 Jul 2017 12:15:49 +0430, esarcush esarcush
<esarcush@gmail.com> said:
EE> Dear all, What is right way to have something like \(
    EE> \frac{\partial A^{i}_{jk}}{\partial x} \)? Indeed, I defined a
    EE> tensor "A~i.j.k" and want to differentiate from it with respect
    EE> to "x" e.g.
For a GiNaC object E its derivative with respect to x is obtained by
  E.diff(x)
--
Vladimir V. Kisil                 http://www.maths.leeds.ac.uk/~kisilv/
  Book:     Geometry of Mobius Transformations     http://goo.gl/EaG2Vu
  Software: Geometry of cycles          http://moebinv.sourceforge.net/
E needs to depend on x. So,

symbol A("A"), x("x");
symbol i_sym("i"), j_sym("j");
idx i(i_sym, 3), j(j_sym, 3);
ex e = indexed(A, i, j);
ex de_dx = e.diff(x);
cout << de_dx << "\n";

returns 0. Thus, what is the way to depend "e" on "x" like undefined functions?

All the bests,

esarcush esarcush

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