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Suppose $f$ is a continuous function with bounded derivatives (if need be, we can also assume $f$ is holomorphic). Can I get bounds for the norm of $n$th derivative of $f$? $f$ is a function of several variables to several variables.

I know if $f$ is from single variable to single variable and is holomorphic, I can use Cauchy's Estimates to bound the nth derivative as:

Suppose $f$ is holomorphic on a neighborhood of the closed ball ${B}(z^*, R)$, and suppose that \begin{align} m := \max \{ |f(z)| : |z - z^*| = r \}, \quad (m < \infty). \end{align} Then \begin{align} \left|f^{(n)}(z^*) \right| \leq \frac{n! \, m}{r^n}. \end{align}

I am looking for a similar result if $f$ is from several variables to several variables.

Edit 1: I should add more details when I say bound on higher-order derivatives. For instance, $f^{(2)}(\mathbf{x})$ would be multiple hessian-like matrices, one for each component of $f$. When I say I want $||f^{(2)}(\mathbf{x})|| \leq M$, I want $M$ that is the supremum of all the upper bounds to the hessian-like matrices.

dbagchi
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  • Pretty much any textbook on functions of several complex variables will cover higher-dimensional Cauchy formula and inequalities. The story is pretty much the same as in the 1-dimensional case. – Moishe Kohan Feb 23 '25 at 21:36
  • @MoisheKohan I couldn't find it on the books I searched or on the net, could you guide me to a resource, please? Many thanks! – dbagchi Feb 23 '25 at 22:00
  • Which books did you try? – Moishe Kohan Feb 23 '25 at 22:14
  • The generalization is immediate, see here for the basic idea. Once you have the integral formula, things follow immediately. – peek-a-boo Feb 24 '25 at 19:53

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