Calculus in Banach spaces: Gateaux derivative and consecuences of the mean value theorem

So far, the examples of (Fréchet) differentiable functions presented are all classical in some sense and even though there was necessary to introduce some new lemmas to compute explicitly the derivative, the computations have been reasonable until now. However, in many practical examples it is not possible to compute the Fréchet derivative in one step. …

Calculus in Banach Spaces: Application to classical functionals

The first two examples presented in the begining of these notes show us that the space of modelling of a PDE is quite related to its formulation. So far we have presented two types of problems: the classical Dirichlet problem and the weak variational problem. The former involves a pointwise statement and the later an …

Calculus in Banach Spaces: Fréchet Derivative.

The study of linear equations, known as linear algebra in the finite dimensional case and as functional analysis in the general case, has furnished powerful and beautiful techniques to prove well-posedness of a huge and diverse amount of problems, like the weak variational problem commented in the last part. Many results like Lax-Milgram theorem, Fredholm …

Nonlinear equations

The main idea of the first part of this work is to introduce some techniques to approach the following nonlinear problem: $latex \displaystyle F(x)=y \ \ \ \ \ (1)&fg=000000$ Where $latex {K\subset X}&fg=000000$ is the feasible set and $latex {F:K\rightarrow Y}&fg=000000$ is any function between topological spaces. Many important problems (in PDE) match with …