# satisfy_mpi

satisfy_mpi, a C code which demonstrates, for a particular circuit, an exhaustive search for solutions of the circuit satisfy problem. This version of the code uses MPI to carry out the solution in parallel.

This problem assumes that we are given a logical circuit of AND, OR and NOT gates, with N binary inputs and a single output. We are to determine all inputs which produce a 1 as the output.

The general problem is NP complete, so there is no known polynomial-time algorithm to solve the general case. The natural way to search for solutions then is exhaustive search.

In an interesting way, this is a very extreme and discrete version of the problem of maximizing a scalar function of multiple variables. The difference is that here we know that both the input and output only have the values 0 and 1, rather than a continuous range of real values!

This problem was a natural candidate for parallel computation, since the individual evaluations of the circuit are completely independent.

### Languages:

satisfy_mpi is available in a C version and a C++ version and a FORTRAN90 version.

### Related Data and codes:

COMMUNICATOR_MPI, a C code which creates new communicators involving a subset of initial set of MPI processes in the default communicator MPI_COMM_WORLD.

HEAT_MPI, a C code which solves the 1D Time Dependent Heat Equation using MPI.

HELLO_MPI, a C code which prints out "Hello, world!" using the MPI parallel codeming environment.

LAPLACE_MPI, a C code which solves Laplace's equation on a rectangle, using MPI for parallel execution.

mpi_test, C codes which illustrate the use of the MPI application code interface for carrying out parallel computatioins in a distributed memory environment.

MULTITASK_MPI, a C code which demonstrates how to "multitask", that is, to execute several unrelated and distinct tasks simultaneously, using MPI for parallel execution.

POISSON_MPI, a C code which computes a solution to the Poisson equation in a rectangle, using the Jacobi iteration to solve the linear system, and MPI 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.

QUAD_MPI, a C code which approximates an integral using a quadrature rule, and carries out the computation in parallel using MPI.

RANDOM_MPI, a C code which demonstrates one way to generate the same sequence of random numbers for both sequential execution and parallel execution under MPI.

RING_MPI, a C code which uses the MPI parallel codeming environment, and measures the time necessary to copy a set of data around a ring of processes.

SATISFY, a C code which solves the circuit satisfy problem.

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.

SEARCH_MPI, a C code which searches integers between A and B for a value J such that F(J) = C, using MPI.

WAVE_MPI, a C code which uses finite differences and MPI to estimate a solution to the wave equation.

### Reference:

1. Michael Quinn,
Parallel codeming in C with MPI and OpenMP,
McGraw-Hill, 2004,
ISBN13: 978-0071232654,
LC: QA76.73.C15.Q55.

### Source Code:

Last revised on 26 June 2020.