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/*
*
* This file is part of MUMPS 5.8.1, released
* on Wed Jul 30 16:49:18 UTC 2025
*
*/
/* Example program using the C interface to the
* double real arithmetic version of MUMPS, dmumps_c.
* We solve the system A x = RHS with
* A = diag(1 2) and RHS = [1 4]^T
* Solution is [1 2]^T */
#include <stdio.h>
#include <string.h>
#include "mpi.h"
#include "dmumps_c.h"
#define JOB_INIT -1
#define JOB_END -2
#define USE_COMM_WORLD -987654
#if defined(MAIN_COMP)
/*
* Some Fortran compilers (COMPAQ fort) define "main" in
* their runtime library while a Fortran program translates
* to MAIN_ or MAIN__ which is then called from "main".
* We defined argc/argv arbitrarily in that case.
*/
int MAIN__();
int MAIN_()
{
return MAIN__();
}
int MAIN__()
{
int argc=1;
char * name = "c_example";
char ** argv ;
#else
int main(int argc, char ** argv)
{
#endif
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 normally still require standard int for C */
/* MUMPS_INT myid, ierr; */
int myid, ierr;
int error = 0;
#if defined(MAIN_COMP)
argv = &name;
#endif
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) {
printf(" (PROC %d) ERROR RETURN: \tINFOG(1)= %d\n\t\t\t\tINFOG(2)= %d\n",
myid, id.infog[0], id.infog[1]);
error = 1;
}
/* Terminate instance. */
id.job=JOB_END;
dmumps_c(&id);
if (myid == 0) {
if (!error) {
printf("Solution is : (%8.2f %8.2f)\n", rhs[0],rhs[1]);
} else {
printf("An error has occured, please check error code returned by MUMPS.\n");
}
}
ierr = MPI_Finalize();
return 0;
}
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