calling fortran 77 from c for arpack

Question

I'm trying to call the fortran function dsaupd from ARPACK. I used the C declaration from netlib-java

  extern void dsaupd_(int *ido, char *bmat, int *n, char *which,
                       int *nev, double *tol, double *resid,
                       int *ncv, double *V, int *ldv,
                       int *iparam, int *ipntr, double *workd,
                       double *workl, int *lworkl, int *info);

then i defined numcols as an int earlier in the program before calling dsaupd with

int ido = 0;
int ncv = 2*numeigs;
int maxiter = 30;
double tol = 1e-13;
double * v = (double *) malloc(numcols * ncv *sizeof(double));
int iparam[11] = {1, 0, maxiter, 1, 0, 0, 1, 0, 0, 0, 0};
int ipntr[11];
double * workd = (double *) malloc(3*numcols*sizeof(double));
int lworkl = ncv*(ncv + 8);
double * workl = (double *) malloc(lworkl*sizeof(double));
int arpack_info = 0;

char bmat = 'I';
char which[2] = {'L', 'M'};
MPI_Barrier(comm);
if (mpi_rank == 0) {
    printf("Here!\n");
    dsaupd_(&ido, &bmat, &numcols, which,
            &numeigs, &tol, vector, 
            &ncv, v, &numcols,
            iparam, ipntr, workd, 
            workl, &lworkl, &arpack_info);
    printf("Here!\n");
}

The code compiles and makes it to the first "Here" printout, but stalls after that. Any idea what I'm doing wrong, or how to debug this call?

1) Don't cast the result of `malloc` & friends in C. 2) Initialisers for compound types must be constant. — too honest for this site, Mar 21 '16 at 01:32
I gave both of those a try, but am still getting a stall. the initializer makes sense (although here maxiter is a constant, so shouldn't be an issue), but why should I not cast the malloc to the correct types? — AatG, Mar 21 '16 at 01:49
`maxiter` is definitively not a constant, but a variable. Even if it was qualified `const`, it would not be a constant. C is not C++, it has no symbolic constants other than the very limited _enum-constants_. — too honest for this site, Mar 21 '16 at 02:08
never mind, the issue was something to do with the way arpack was compiled. I got the same freezing when I tried to run their sample code. So I switched to arpack-ng and everything worked. — AatG, Mar 21 '16 at 03:34

score 1 · Accepted Answer · answered Mar 21 '16 at 03:35

1

I think even though arpack was compiling on my system, it was linking incorrectly. Switching to arpack-ng fixed the issue.

answered Mar 21 '16 at 03:35

AatG

685
8
23

calling fortran 77 from c for arpack

1 Answers1