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by Eebster the Great
Thu Oct 29, 2009 5:52 am UTC
Forum: Mathematics
Topic: Discontinuous derivative of an explicitly defined function
Replies: 18
Views: 4361

Discontinuous derivative of an explicitly defined function

I am having trouble thinking of explicitly defined, differentiable functions with discontinuous derivatives in one dimension. This has been a problem that has bothered me since BC Calc, when I was presented an example of an integrable, discontinuous function defined piecemeal by its derivative. This...
by Eebster the Great
Thu Oct 29, 2009 5:34 am UTC
Forum: Mathematics
Topic: Taylor Series
Replies: 10
Views: 913

Re: Taylor Series

My preferred proof for Euler's formula is simply solving a second-order differential equation, although to be rigorous it technically requires proving some differentiation formulae for complex numbers. d^2/dx^2 e^(i x) = d/dx i e^(i x) = i^2 e^(i x) = -e^(i x) So solve the diff eq: d^2y/dx^2 = -y Th...
by Eebster the Great
Thu Oct 29, 2009 5:23 am UTC
Forum: The Help Desk
Topic: Cannot login on Firefox
Replies: 4
Views: 575

Cannot login on Firefox

This problem is odd, but I cannot login to this forum on Firefox, which is by far my prefered browser. After clicking "submit" in the login form, I do go to the page saying I logged in, but when it redirects me to the forum (or anywhere else) it clearly indicates that I am NOT logged in, a...

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