Diff, derivative does not exist

10 次查看（过去 30 天）
James_111
James_111 2019-1-27
编辑： Walter Roberson 2019-1-27
My code is:
fun=@(x) abs(x-1);
pfun=@(x) diff(fun(x),x);
feval(pfun,1)
It didn't return any answer after running the code. My general point, if we want to use Matlab to take the derivative of a function, but the derivative of this funtion does not exist everywhere (like the point 1 in fun(x)). How Matlab return the value? If there are infinite numbers of such points, how Matlab deal with this issue? Any help is very appreciated!
  4 个评论
显示 2更早的评论
Walter Roberson
Walter Roberson 2019-1-27
编辑：Walter Roberson 2019-1-27
You are not doing a symbolic derivative. You are evaluating pfun(1) which is pfun with numeric input. You pass that numeric input to abs(x-1), getting a numeric output. Your diff() of a numeric input is finite differences, not derivative.
James_111
James_111 2019-1-27
Thank you so much for pointing out the "finite difference", Walter!

请先登录，再进行评论。

请先登录，再回答此问题。

回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Just for fun 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