Read the full paper at: http://www.scirp.org/journal/PaperInformation.aspx?PaperID=50042 DOI: 10.4236/jemaa.2014.610031 Author(s) Serigne Bira Gueye, Kharouna Talla, Cheikh Mbow ABSTRACT An innovative, extremely fast and accurate method is presented for Neumann-Dirichlet and Dirichlet-Neumann boundary problems for the Poisson equation, and the diffusion and wave equation in quasi-stationary regime; using the finite difference method, in one dimensional case. eww141009gjr Two novels matrices are determined allowing a direct and exact formulation of the solution of the Poisson equation. Verification is also done considering an interesting potential problem and the sensibility is determined. This new method has an algorithm complexity of O(N), its truncation error goes like O(h2), and it is more precise and faster than the Thomas algorithm. KEYWORDS 1D Poisson Equation, Finite Difference Method, Neumann-Dirichlet, Dirichlet-Neumann, Boundary Problem, Tridiagonal Matrix Inversion, Thomas Algorithm