Approximation of several variables functions by products or sums of one variable functions

Decomposition of several variables functions by means of functions of one variable was a fundamental problem, studied by mathematicians, and the specially by KOLMOGOROV school. This question is closely connected with optimization and optimal control and with multiple integrals calculus. These problems have been investigated by Professor Y. Cherruault and colleagues, using the ALIENOR method, which is based on α‐dense curves. The decomposition method of Adomian can be coupled with global optimization for solving optimal control problems. Aim is to calculate multiple integrals by a special decomposition of the function using an orthonormal basis of functions. Presents also new methods for approximating a n‐variables function by means of the sum of product of n functions only depending on a single variable. Applications to multi‐variables optimization problems and optimal control system are described.