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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_save_restore";
char ** argv ;
#else
int main(int argc, char ** argv)
{
#endif
DMUMPS_STRUC_C id_save,id_restore;
MUMPS_INT n = 2;
MUMPS_INT8 nnz = 2;
MUMPS_INT irn[] = {1,2};
MUMPS_INT jcn[] = {1,2};
double a[2];
double rhs[2];
int error = 0;
/* 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;
#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 MUMPS save instance. Use MPI_COMM_WORLD */
id_save.comm_fortran=USE_COMM_WORLD;
id_save.par=1; id_save.sym=0;
id_save.job=JOB_INIT;
dmumps_c(&id_save);
/* Define the problem on the host */
if (myid == 0) {
id_save.n = n; id_save.nnz =nnz; id_save.irn=irn; id_save.jcn=jcn;
id_save.a = a;
}
#define ICNTL(I) icntl[(I)-1] /* macro s.t. indices match documentation */
/* No outputs */
id_save.ICNTL(1)=-1; id_save.ICNTL(2)=-1;
id_save.ICNTL(3)=-1; id_save.ICNTL(4)=0;
/* Call the MUMPS package on the save instance (analyse and factorization). */
id_save.job=4;
dmumps_c(&id_save);
/* MUMPS save feature on the save instance. */
strcpy(id_save.save_prefix,"csave_restore");
strcpy(id_save.save_dir,"/tmp");
if (myid == 0) {
printf("Saving MUMPS instance in %s with prefix %s.\n",
id_save.save_dir, id_save.save_prefix);
}
id_save.job=7;
dmumps_c(&id_save);
if (id_save.infog[0]<0) {
printf("\n (PROC %d) ERROR RETURN: \tINFOG(1)= %d\n\t\t\t\tINFOG(2)= %d\n",
myid, id_save.infog[0], id_save.infog[1]);
error = 1;
} else if (myid == 0) {
printf(" DONE\n\n");
}
/* Terminate the save instance. */
id_save.job=JOB_END;
dmumps_c(&id_save);
if (!error) {
/* Initialize MUMPS restore instance. Use MPI_COMM_WORLD */
id_restore.comm_fortran=USE_COMM_WORLD;
id_restore.par=1; id_restore.sym=0;
id_restore.job=JOB_INIT;
dmumps_c(&id_restore);
/* Define the rhs on the host */
if (myid == 0) {
id_restore.rhs = rhs;
}
/* No outputs */
id_save.ICNTL(1)=-1; id_save.ICNTL(2)=-1;
id_save.ICNTL(3)=-1; id_save.ICNTL(4)=0;
/* MUMPS restore feature on restore instance. */
if (myid == 0) {
printf("Restoring MUMPS instance in %s with prefix %s.\n",
id_save.save_dir, id_save.save_prefix);
}
strcpy(id_restore.save_prefix,"csave_restore");
strcpy(id_restore.save_dir,"/tmp");
id_restore.job=8;
dmumps_c(&id_restore);
if (id_save.infog[0]<0) {
printf("\n (PROC %d) ERROR RETURN: \tINFOG(1)= %d\n\t\t\t\tINFOG(2)= %d\n",
myid, id_save.infog[0], id_save.infog[1]);
error = 1;
} else if (myid == 0) {
printf(" DONE\n\n");
}
}
if (!error) {
/* Call the MUMPS package on restore instance (solve). */
if (myid == 0) {
printf("Calling MUMPS package (solve).\n");
}
id_restore.job=3;
dmumps_c(&id_restore);
if (id_save.infog[0]<0) {
printf("=> (PROC %d) ERROR RETURN: \tINFOG(1)= %d\n\t\t\t\tINFOG(2)= %d\n",
myid, id_save.infog[0], id_save.infog[1]);
error = 1;
} else if (myid == 0) {
printf(" DONE\n\n");
}
/* Deletes the saved and the OOC files. */
if (myid == 0) {
printf("Removing save files.\n");
}
id_restore.job=-3;
dmumps_c(&id_restore);
if (id_save.infog[0]<0) {
printf("=> (PROC %d) ERROR RETURN: \tINFOG(1)= %d\n\t\t\t\tINFOG(2)= %d\n",
myid, id_save.infog[0], id_save.infog[1]);
error = 1;
} else if (myid == 0) {
printf(" DONE\n\n");
}
/* Terminate the restore instance. */
id_restore.job=JOB_END;
dmumps_c(&id_restore);
}
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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