poisson_serial, a FORTRAN77 code which computes an approximate solution to the Poisson equation in a 2D rectangular region.
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_SERIAL is intended as a starting point for the implementation of a parallel version, using, for instance, MPI.
The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.
poisson_serial is available in a C version and a C++ version and a FORTRAN77 version and a FORTRAN90 version and a MATLAB version.
fem2d_poisson_rectangle, a FORTRAN77 program which solves the 2D Poisson equation on a rectangle, using the finite element method, and piecewise quadratic triangular elements.
fft_serial, a FORTRAN77 program which demonstrates the computation of a Fast Fourier Transform, and is intended as a starting point for implementing a parallel version.
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HEATED_PLATE, a FORTRAN77 program 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.
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MG_SERIAL, a FORTRAN77 program which a serial version of the NAS Parallel Benchmark MG (MultiGrid).
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MXM_SERIAL, a FORTRAN77 program which sets up a matrix multiplication problem A=B*C, intended as a starting point for implementing a parallel version.
POISSON_OPENMP, a FORTRAN77 program which computes an approximate solution to the Poisson equation in a rectangle, using the Jacobi iteration to solve the linear system, and OpenMP to carry out the Jacobi iteration in parallel.
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SEARCH_SERIAL, a FORTRAN77 program which searches the integers from A to B for a value J such that F(J) = C. this version of the program is intended as a starting point for a parallel approach.
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