Symbolic derivative in a sum

4 次查看（过去 30 天）
uranus
uranus 2024-3-14
评论： David Goodmanson 2024-3-15
I have this expression and I want to evaluate the derivative over p where A_m has a form like that:
It don't know even where to start from. Is there any way to do it ?

请先登录，再回答此问题。

回答（1 个）

David Goodmanson
David Goodmanson 2024-3-14
编辑：David Goodmanson 2024-3-14
Hello OG,
If you know d/dp G for the elements of G, you can use
d/dp G^-1 = -G^-1 (d/dp G) G^-1
which is all right numerically, But if you want to do the whole thing symbolically, unless the size of G is really small this will turn into a huge intractable mess of symbolic spaghetti very quickly.
  2 个评论
uranus
uranus 2024-3-14
编辑：uranus 2024-3-14
I have already tried that, but then it turns into (also a mess of) normal differentiation, but I can write it explicitly. Thus, is it not anymore symbolic, right? The system is of the order of 20 but I think this is sufficient to get the spaghetti!
David Goodmanson
David Goodmanson 2024-3-15
If you know (d/dp G) either symbolically or numerically then you can get it numerically, and after that it would appear that numerical evaluation of the expression -G^-1 (d/dp G) G^-1 for a 20x20 should work reasonably well, unless G is close to being singular and has a bad condition number..

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Symbolic Math Toolbox 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by