poisson_2d


poisson_2d, an Octave code which computes an approximate solution to the Poisson equation in the unit square, using finite differences and Jacobi iteration.

The version of Poisson's equation being solved here is

        - ( d/dx d/dx + d/dy d/dy ) U(x,y) = F(x,y)
      
over the rectangle 0 <= X <= 1, 0 <= Y <= 1, with exact solution
        U(x,y) = sin ( pi * x * y )
      
so that
        F(x,y) = pi^2 * ( x^2 + y^2 ) * sin ( pi * x * y )
      
and with Dirichlet boundary conditions along the lines x = 0, x = 1, y = 0 and y = 1. (The boundary conditions will actually be zero in this case, but we write up the problem as though we didn't know that, which makes it easy to change the problem later.)

We compute an approximate solution by discretizing the geometry, assuming that DX = DY, and approximating the Poisson operator by

        ( U(i-1,j) + U(i+1,j) + U(i,j-1) + U(i,j+1) - 4*U(i,j) ) / dx /dy
      
Along with the boundary conditions at the boundary nodes, we have a linear system for U. We can apply the Jacobi iteration to estimate the solution to the linear system.

poisson is intended as a starting point for the implementation of a parallel version, using, for instance, MPI.

Licensing:

The computer code and data files described and made available on this web page are distributed under the MIT license

Languages:

poisson is available in a C version and a MATLAB version and an Octave version.

Related Data and Programs:

poisson_2d_test

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heated_plate, an Octave code which solves the steady (time independent) heat equation in a 2D rectangular region, and is intended as a starting point for implementing a parallel version.

md, an Octave code which carries out a molecular dynamics simulation, and is intended as a starting point for implementing a parallel version.

quad, an Octave code which approximates an integral using a quadrature rule, and is intended as a starting point for parallelization exercises.

Source Code:


Last revised on 18 June 2023.