PRIME_OPENMP, a C++ code which counts the number of primes between 1 and N, using OpenMP to carry out the calculation in parallel.
The algorithm is completely naive. For each integer I, it simply checks whether any smaller J evenly divides it. The total amount of work for a given N is thus roughly proportional to 1/2*N^2.
This program is mainly a starting point for investigations into parallelization.
Here are the counts of the number of primes for some selected values of N:
|N||Pi(N), Number of Primes|
In the BASH shell, the program could be run with 2 threads using the commands:
export OMP_NUM_THREADS=2 ./prime_openmp
The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.
PRIME_OPENMP is available in a C version and a C++ version and a FORTRAN90 version.
DIJKSTRA_OPENMP, a C++ code which uses OpenMP to parallelize a simple example of Dijkstra's minimum distance algorithm for graphs.
FFT_OPENMP, a C++ code which demonstrates the computation of a Fast Fourier Transform in parallel, using OpenMP.
HEATED_PLATE_OPENMP, a C++ code which solves the steady (time independent) heat equation in a 2D rectangular region, using OpenMP to run in parallel.
HELLO_OPENMP, a C++ code which prints out "Hello, world!" using the OpenMP parallel programming environment.
JACOBI_OPENMP, a C++ code which illustrates the use of the OpenMP application program interface to parallelize a Jacobi iteration solving A*x=b.
MD_OPENMP, a C++ code which carries out a molecular dynamics simulation in parallel, using OpenMP.
MULTITASK_OPENMP, a C++ code which demonstrates how to "multitask", that is, to execute several unrelated and distinct tasks simultaneously, using OpenMP for parallel execution.
MXM_OPENMP, a C++ code which computes a dense matrix product C=A*B, using OpenMP for parallel execution.
openmp_test, C++ codes which illustrate the use of the OpenMP application program interface for carrying out parallel computations in a shared memory environment.
POISSON_OPENMP, a C++ code 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.
PRIME_MPI, a C++ code which counts the number of primes between 1 and N, using MPI for parallel execution.
PRIME, a C++ code which counts the number of primes between 1 and N, intended as a starting point for the creation of a parallel version.
QUAD_OPENMP, a C++ code which approximates an integral using a quadrature rule, and carries out the computation in parallel using OpenMP.
RANDOM_OPENMP, a C++ code which illustrates how a parallel program using OpenMP can generate multiple distinct streams of random numbers.
SATISFY_OPENMP, a C++ code which demonstrates, for a particular circuit, an exhaustive search for solutions of the circuit satisfy problem, using OpenMP for parallel execution.
SCHEDULE_OPENMP, a C++ code which demonstrates the default, static, and dynamic methods of "scheduling" loop iterations in OpenMP to avoid work imbalance.
SGEFA_OPENMP, a C++ code which reimplements the SGEFA/SGESL linear algebra routines from LINPACK for use with OpenMP.
TIMER, C++ codes which demonstrate how to compute CPU time or elapsed time.
ZIGGURAT_OPENMP, a C++ code which demonstrates how the ZIGGURAT library can be used to generate random numbers in an OpenMP parallel program.