Example code

#include <iostream>
#include <cstdlib>
#include <rocalution.hpp>

using namespace rocalution;

int main(int argc, char* argv[])
{
    if(argc == 1)
    {
        std::cerr << argv[0] << " <matrix> [Num threads]" << std::endl;
        exit(1);
    }

    // Initialize rocALUTION
    init_rocalution();

    if(argc > 2)
    {
        set_omp_threads_rocalution(atoi(argv[2]));
    }

    // Print rocALUTION backend info
    info_rocalution();

    // rocALUTION objects
    LocalMatrix<double> mat;
    LocalVector<double> rhs;
    LocalVector<double> x;
    LocalVector<double> e;

    // Read mtx matrix from file
    mat.ReadFileMTX(std::string(argv[1]));

    // Move rocALUTION objects to accelerator device (if available)
    mat.MoveToAccelerator();
    x.MoveToAccelerator();
    rhs.MoveToAccelerator();
    e.MoveToAccelerator();

    // Allocate vectors
    x.Allocate("x", mat.GetN());
    rhs.Allocate("rhs", mat.GetM());
    e.Allocate("e", mat.GetN());

    // Linear Solver
    CG<LocalMatrix<double>, LocalVector<double>, double> ls;

    // Preconditioner
    Jacobi<LocalMatrix<double>, LocalVector<double>, double> p;

    // Generate rhs vector such that x = 1
    e.Ones();
    mat.Apply(e, &rhs);
    x.Zeros();

    // Set solver operator
    ls.SetOperator(mat);

    // Set solver preconditioner
    ls.SetPreconditioner(p);

    // Build solver and preconditioner
    ls.Build();

    // Verbose output
    ls.Verbose(2);

    // Print matrix info
    mat.Info();

    // Start time measurement
    double tick, tack;
    tick = rocalution_time();

    // Solve linear system Ax = rhs
    ls.Solve(rhs, &x);

    // End time measurement
    tack = rocalution_time();
    std::cout << "Solver execution:" << (tack - tick) / 1000000 << " sec" << std::endl;

    // Clear solver
    ls.Clear();

    // Compute L2 norm of then error
    e.ScaleAdd(-1.0, x);
    double error = e.Norm();

    std::cout << "||e - x||_2 = " << error << "\n";

    // Stop rocALUTION
    stop_rocalution();

    return 0;
}

To compile and run the example, past above code into a file rocalution_cg_example.cpp.

Compiling rocALUTION example

To compile rocalution_cg_example.cpp, a standard C++ compiler can be used (e.g. g++):

g++ -O3 -o rocalution_cg_example rocalution_cg_example.cpp -I/opt/rocm/include -L/opt/rocm/lib -lrocalution

Running rocALUTION example

The compiled rocalution_cg_example can be executed by

./rocalution_cg_example <matrix.mtx>

where matrix.mtx is a matrix in Matrix-Market format. Different matrices can be obtained from e.g. SuiteSparse Matrix Collection.