Now showing items 1-5 of 5

    • A counterexample in the theory of linear singularly perturbed systems 

      Naulin, Raúl
      In this note we compare the bounded solutions of the linear singularly perturbed system ε X' = A (t) x + f (t), with the solutions of the algebraic system A (t) x + f (t) = 0.  Here A and  f  are bounded C1 functions with ...
      Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. 
    • A remark on exponential dichotomies 

      Naulin, Raúl
      A proof of the existence of an exponential dichotomy for the linear system x'(t) = A(t)x(t) is given, based on the admissibility of the pair (B(∞), BA(∞)), where B(∞) is the space of continuous functions on the semiaxis J ...
      Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. 
    • Una aplicación del teorema de liberalización de hartman 

      Naulin, Raúl
      In this note we consider the ordinary differential equation U' = AU +f(t, U), where A is a real, constant, n x n matrix with eigenvalues satisfying Reλ = 0. We assume that the solution U = 0 of the system U' =A U is stable. ...
      Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. 
    • Differential equations associated to algebraic functions and their solutions 

      Pabst, Carlos; Naulin, Raúl
      A method to find the general solution of algebraic equations, including the quintic, is presented. The procedure is essentially based on the analytical properties of the algebraic functions and leads to the solution of ...
      Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. 
    • The roots of a polynomial depend continuously on its coefficients 

      Naulin, Raúl; Pabst, Carlos
      An elementary proof is given of the continuous dependence of the roots of a polynomial on its coefficients.
      Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas.