Re: ** says: Definition: sum{i in N} i = 0

On 9 Jul., 21:56, Virgil <vir...@xxxxxxxxxxx> wrote:

Then according to WM, every derivative must always equal 1 at all
points, and f(x) = |x| must have a derivative at x = 0, and lots more.

That's nonsense.

Maybe, but it is WM's nonsense, not mine, to argue that functions must
continuous at points outside their domains.

Continuous functions must be continuous. The derivative of |x| is not
continuous but -1 for negative x and +1 for positive x. In contrast
sinx/x is continuous. Your example fails.

Regards, WM


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