analytic function and all of its (infinitely many) derivatives at a single point, then
that function is unique, and you know it everywhere. In other words, only one
analytic function can pass through that point with those particular values for its
derivatives. To be dealing with functions so nicely restricted relieves us from
many of the worries that keep pure mathematicians entertained.
As an example, assume that an analytic function of one variable passes
through the origin where its first derivative is equal to 2, and all other derivatives
are zero. The analytic function y ¼ 2x uniquely satisfies that condition and is
thus that function. Of all the analytic functions that pass through the origin,
only this one meets the stated requirements.
Thus when ...