SuiteSparse(4.5.1)'s SPQR - calling to cholmod_allocate_triplet always returns NULL

Question

I am trying to use SuiteSparse SPQR to solve a linear equation system x = A\\b; my A matrix is sparse and it is a rectangular matrix so I chose SPQR to solve this. I built SuiteSparse using MS Visual Studio 2012 on Windows 7 x64 using those provided by https://github.com/jlblancoc/suitesparse-metis-for-windows .

In order to test the function, I modified the spqr_example project to allocate tripets before converting to sparse matrix, instead of originally reading input from stdin to create a sparse matrix. I input a small A and b matrix for testing. The program compiled successfully. I debugged the program and found that my call to cholmod_allocate_triplet() has failed because in the declaration of this function it has this code below:

RETURN_IF_NULL_COMMON (NULL) ;

This always return false (even though my common starts successfully).

I don't want to explicitly make change to this line, as I might have make mistake somewhere or I forgot to do something I have to do because I am new to use the library.

Can anybody help give me some suggestion on how to make my program run properly? My code below is modified from the provided spqr_example. Thank you very much.

#include <iostream>
#include "SuiteSparseQR.hpp"

int main (int argc, char **argv)
{
cholmod_common Common, *cc ;
cholmod_sparse *A ;
cholmod_dense *X, *B, *Residual ;
double rnorm, one [2] = {1,0}, minusone [2] = {-1,0} ;
int mtype ;
// start CHOLMOD
cc = &Common ;
cholmod_l_start (cc) ;

// load A
//A = (cholmod_sparse *) cholmod_l_read_matrix (stdin, 1, &mtype, cc) ;

        // A = [ 1  0  0  0; 
        //      -1  1  0  0; ...
        //       0 -1  1  0; ...
        //       0  0 -1  1; ...
        //       0  0  0 -1];
        int row[] = {0, 1, 1, 2, 2, 3, 3, 4};
        int col[] = {0, 0, 1, 1, 2, 2, 3, 3};
        double val[] = {1.0, -1.0, 1.0, -1.0, 1.0, -1.0, 1.0, -1.0};
        int numEq = 5;
        int numElement = 8;
        int numSol = 4;
        double b[] = {5.0, -5.0, 2.0, 1.0, 0.0};

cholmod_triplet* triplet = cholmod_allocate_triplet(5,4,5*4,0,CHOLMOD_REAL,cc);
int * triplet_i = (int *)(triplet->i);
int * triplet_j = (int *)(triplet->j);
double * triplet_x = (double *)(triplet->x);
for (int ne=0; ne<numElement; ne++)
{
    triplet_i[triplet->nnz] = row[ne];
    triplet_j[triplet->nnz] = col[ne];
    triplet_x[triplet->nnz] = val[ne];

    triplet->nnz++;
}

// Convert triplet to sparse matrix
A = cholmod_triplet_to_sparse(triplet, numElement, cc);
cholmod_free_triplet(&triplet, cc);

// B = ones (size (A,1),1)
//B = cholmod_l_ones (A->nrow, 1, A->xtype, cc) ;
B = cholmod_l_zeros(numEq, 1, CHOLMOD_REAL, cc);
for (int ne=0; ne<numEq; ne++)
{
    ((double *)(B->x))[ne] = val[ne];
}

// X = A\B
X = SuiteSparseQR<double>(A,B,cc);
//X = SuiteSparseQR <double> (A, B, cc) ;

// Print out the result
double *sol = static_cast<double *>(malloc(sizeof(X->x)));
sol = (double *)(X->x);
for (int r=0; r<numSol; r++)
{
    std::cout << "x[" << r << "] = " << sol << std::endl;
    sol++;
}

///// END HERE

// rnorm = norm (B-A*X)
Residual = cholmod_l_copy_dense (B, cc) ;
cholmod_l_sdmult (A, 0, minusone, one, X, Residual, cc) ;
rnorm = cholmod_l_norm_dense (Residual, 2, cc) ;
printf ("2-norm of residual: %8.1e\n", rnorm) ;
printf ("rank %ld\n", cc->SPQR_istat [4]) ;
// free everything and finish CHOLMOD
cholmod_l_free_dense (&Residual, cc) ;
cholmod_l_free_sparse (&A, cc) ;
cholmod_l_free_dense (&X, cc) ;
cholmod_l_free_dense (&B, cc) ;
cholmod_l_finish (cc) ;
return (0) ;
}

Answer 1

I have finally find out why my program broke after the line below

cholmod_triplet* triplet = cholmod_allocate_triplet(5,4,5*4,0,CHOLMOD_REAL,cc);

as the result of the cholmod_allocate_triplet() internally calling RETURN_IF_NULL_COMMON (NULL), which return false.

The reason is that I start the process calling

cholmod_l_start (cc) ;

which is the long int version of cholmod_start().

To fix the problem, I have to call cholmod_l_allocate_triplet() instead of cholmod_allocate_triplet() as well as change all other functions to use cholmod_l instead of only calling cholmod_