how to compile a c++ program

[xiaorong117]

• We solve the system A x = RHS with
• A = diag(1 2) and RHS = [1 4]^T
• Solution is [1 2]^T */

#include

#include "mpi.h"
#include "dmumps_c.h"

#define JOB_INIT -1
#define JOB_END -2
#define USE_COMM_WORLD -987654

int main(int argc, char ** argv)
{
DMUMPS_STRUC_C id;
MUMPS_INT n = 2;
MUMPS_INT8 nnz = 2;
MUMPS_INT irn[] = {1,2};
MUMPS_INT jcn[] = {1,2};
double a[2];
double rhs[2];

/* When compiling with -DINTSIZE64, MUMPS_INT is 64-bit but MPI
ilp64 versions may still require standard int for C interface. /
/ MUMPS_INT myid, ierr; */
int myid, ierr;
int error = 0;

ierr = MPI_Init(&argc, &argv);
ierr = MPI_Comm_rank(MPI_COMM_WORLD, &myid);
/* Define A and rhs */
rhs[0]=1.0;rhs[1]=4.0;
a[0]=1.0;a[1]=2.0;

/* Initialize a MUMPS instance. Use MPI_COMM_WORLD */
id.comm_fortran=USE_COMM_WORLD;
id.par=1; id.sym=0;
id.job=JOB_INIT;
dmumps_c(&id);

/* Define the problem on the host /
if (myid == 0) {
id.n = n; id.nnz =nnz; id.irn=irn; id.jcn=jcn;
id.a = a; id.rhs = rhs;
}
#define ICNTL(I) icntl[(I)-1] / macro s.t. indices match documentation /
/ No outputs */
id.ICNTL(1)=-1; id.ICNTL(2)=-1; id.ICNTL(3)=-1; id.ICNTL(4)=0;

/* Call the MUMPS package (analyse, factorization and solve). */
id.job=6;
dmumps_c(&id);

if (id.infog[0]<0) {
std::cerr << " (PROC " << myid <<
") ERROR RETURN: \tINFOG(1)= " << id.infog[0] <<
"\n\t\t\t\tINFOG(2)= " << id.infog[1] << "\n";
error = 1;
}

/* Terminate instance. */
id.job=JOB_END;
dmumps_c(&id);
if (myid == 0) {
if (!error)
std::cout << "Solution is : (" << rhs[0] << " " << rhs[1] << ")\n";
else
std::cerr << "An error has occured, please check error code returned by MUMPS.\n";
}
ierr = MPI_Finalize();
return 0;
}

[xiaorong117]

so i have to modify my c++ code into c style to complie?

[scivision]

No, I added an example at the bottom of Readme.md just now

---

To build the example, first "install" the MUMPS package-the default install location is under the MUMPS build/local directory:

cmake --install build

cmake -S example -B example/build -DMUMPS_ROOT=build/local

cmake --build example/build

Using binary libraries

Linking the MUMPS binaries into a user-program is project-dependant.
An example using the examples in this project with GNU GCC, using the "mpicxx" MPI compiler wrapper:

mpicxx ./example/d_example.cpp -I./build/local/include -L./build/local/lib -ldmumps -lmumps_common -lpord -lscalapack -lblacs -llapack -lblas -lgfortran

[xiaorong117]

Just now, i compiled this d_example.cpp by a modified makefile. And the program goes well. Thanks!