Example #1
0
File: misc.c Project: cvxopt/smcp
static PyObject *phase1_sdp
(PyObject *self, PyObject *args, PyObject *kwrds) {

  matrix *u;
  spmatrix *Ai,*Ao;
  int_t k,i,j,n,m,nnz,nz,col;


  if(!PyArg_ParseTuple(args,"OO",&Ai,&u)) return NULL;
  n = (int_t) sqrt((double)SP_NROWS(Ai));
  m = SP_NCOLS(Ai) - 1;
  nnz = SP_NNZ(Ai) - SP_COL(Ai)[1] + 1 + m + n + 1;

  Ao = SpMatrix_New((n+2)*(n+2),m+2,nnz,DOUBLE);
  if (!Ao) return PyErr_NoMemory();

  // A_0
  SP_VALD(Ao)[0] = 1.0;
  SP_ROW(Ao)[0] = n*(n+2)+n;
  SP_COL(Ao)[0] = 0;
  SP_COL(Ao)[1] = 1;

  // A_i, i=1,..,m
  for (i=1;i<=m;i++){
    k = SP_COL(Ao)[i];
    nz = SP_COL(Ai)[i+1]-SP_COL(Ai)[i]; // nonzeros in Ai
    // copy Ai
    memcpy(SP_VALD(Ao)+k,SP_VALD(Ai)+SP_COL(Ai)[i],nz*sizeof(double));
    // insert -u[i]
    SP_VALD(Ao)[k+nz] = -MAT_BUFD(u)[i-1];
    // update row colptr
    SP_COL(Ao)[i+1] = SP_COL(Ao)[i]+nz+1;
    // generate row indices
    for (j=0;j<nz;j++) {
      col = SP_ROW(Ai)[SP_COL(Ai)[i]+j] / n;
      SP_ROW(Ao)[k+j] = SP_ROW(Ai)[SP_COL(Ai)[i]+j] + col*2;
    }
    SP_ROW(Ao)[k+nz] = n*(n+2)+n;
  }
  // last constraint
  k = SP_COL(Ao)[m+1];
  for (i=0;i<n;i++){
    SP_VALD(Ao)[k+i] = 1.0;
    SP_ROW(Ao)[k+i] = i*(n+2)+i;
  }
  SP_VALD(Ao)[k+n] = 1.0;
  SP_ROW(Ao)[k+n] = (n+2)*(n+2)-1;
  SP_COL(Ao)[m+2] = SP_COL(Ao)[m+1] + n + 1;

  return (PyObject*) Ao;
}
Example #2
0
static PyObject* getfactor(PyObject *self, PyObject *args)
{
    PyObject *F;
    cholmod_factor *Lf;
    cholmod_sparse *Ls;
#if PY_MAJOR_VERSION >= 3
    const char *descr;
#else
    char *descr;
#endif

    if (!set_options()) return NULL;
    if (!PyArg_ParseTuple(args, "O", &F)) return NULL;

#if PY_MAJOR_VERSION >= 3
    if (!PyCapsule_CheckExact(F) || !(descr = PyCapsule_GetName(F)))
        err_CO("F");
    if (strncmp(descr, "CHOLMOD FACTOR", 14))
        PY_ERR_TYPE("F is not a CHOLMOD factor");
    Lf = (cholmod_factor *) PyCapsule_GetPointer(F, descr);
#else
    if (!PyCObject_Check(F)) err_CO("F");
    descr = PyCObject_GetDesc(F);
    if (!descr || strncmp(descr, "CHOLMOD FACTOR", 14))
        PY_ERR_TYPE("F is not a CHOLMOD factor");
    Lf = (cholmod_factor *) PyCObject_AsVoidPtr(F);
#endif

    /* Check factorization */
    if (Lf->xtype == CHOLMOD_PATTERN)
        PY_ERR(PyExc_ValueError, "F must be a numeric Cholesky factor");

    if (!(Ls = CHOL(factor_to_sparse)(Lf, &Common)))
        return PyErr_NoMemory();

    spmatrix *ret = SpMatrix_New(Ls->nrow, Ls->ncol, Ls->nzmax,
       (Ls->xtype == CHOLMOD_REAL ? DOUBLE : COMPLEX));
    if (!ret) {
        CHOL(free_sparse)(&Ls, &Common);
        return PyErr_NoMemory();
    }

    memcpy(SP_COL(ret), Ls->p, (Ls->ncol+1)*sizeof(int_t));
    memcpy(SP_ROW(ret), Ls->i, (Ls->nzmax)*sizeof(int_t));
    memcpy(SP_VAL(ret), Ls->x, (Ls->nzmax)*E_SIZE[SP_ID(ret)]);
    CHOL(free_sparse)(&Ls, &Common);

    return (PyObject *)ret;
}
Example #3
0
File: misc.c Project: cvxopt/smcp
static PyObject *Av_to_spmatrix
(PyObject *self, PyObject *args, PyObject *kwrds)
{
  PyObject *scale = Py_False;
  spmatrix *Av,*Ip,*Jp;
  int_t i,j,n,nnz,c,ci,p,q;
  char *kwlist[] = {"Av","Ip","Jp","j","n","scale",NULL};

  if (!PyArg_ParseTupleAndKeywords(args, kwrds, "OOOnn|O",
				   kwlist, &Av,&Ip,&Jp,&j,&n, &scale))
    return NULL;

  p = SP_COL(Av)[j];
  nnz = SP_COL(Av)[j+1]-p;
  spmatrix *Aj = SpMatrix_New(n,n,nnz,DOUBLE);
  if (!Aj) return PyErr_NoMemory();

  // Generate col-ptr and row index
  SP_COL(Aj)[0] = 0;
  if (scale==Py_False) {
    for (ci=0,i=0;i<nnz;i++) {
      q = SP_ROW(Av)[p+i];
      SP_ROW(Aj)[i] = MAT_BUFI(Ip)[q];
      c = MAT_BUFI(Jp)[q];
      SP_VALD(Aj)[i] = SP_VALD(Av)[p+i];
      while (ci < c)
	SP_COL(Aj)[++ci] = i;
    }
    while (ci < n)
      SP_COL(Aj)[++ci] = nnz;
  }
  else {
    for (ci=0,i=0;i<nnz;i++) {
      q = SP_ROW(Av)[p+i];
      SP_ROW(Aj)[i] = MAT_BUFI(Ip)[q];
      c = MAT_BUFI(Jp)[q];
      SP_VALD(Aj)[i] = SP_VALD(Av)[p+i];
      if (c == SP_ROW(Aj)[i]) SP_VALD(Aj)[i] *= 0.5; // scale diag. element
      while (ci < c)
	SP_COL(Aj)[++ci] = i;
    }
    while (ci < n)
      SP_COL(Aj)[++ci] = nnz;
  }

  return (PyObject *) Aj;
}
Example #4
0
static PyObject* splinsolve(PyObject *self, PyObject *args,
    PyObject *kwrds)
{
    spmatrix *A, *B, *X;
    matrix *P=NULL;
    int n, nnz;
    cholmod_sparse *Ac=NULL, *Bc=NULL, *Xc=NULL;
    cholmod_factor *L=NULL;
#if PY_MAJOR_VERSION >= 3
    int uplo_='L';
#endif
    char uplo='L';
    char *kwlist[] = {"A", "B", "p", "uplo", NULL};

    if (!set_options()) return NULL;
#if PY_MAJOR_VERSION >= 3
    if (!PyArg_ParseTupleAndKeywords(args, kwrds, "OO|OC", kwlist, &A,
        &B, &P, &uplo_)) return NULL;
    uplo = (char) uplo_;
#else
    if (!PyArg_ParseTupleAndKeywords(args, kwrds, "OO|Oc", kwlist, &A,
        &B, &P, &uplo)) return NULL;
#endif

    if (!SpMatrix_Check(A) || SP_NROWS(A) != SP_NCOLS(A))
        PY_ERR_TYPE("A is not a square sparse matrix");
    n = SP_NROWS(A);
    nnz = SP_NNZ(A);

    if (!SpMatrix_Check(B) || SP_ID(A) != SP_ID(B))
        PY_ERR_TYPE("B must be a sparse matrix of the same type as A");
    if (SP_NROWS(B) != n)
        PY_ERR(PyExc_ValueError, "incompatible dimensions for B");

    if (P) {
        if (!Matrix_Check(P) || MAT_ID(P) != INT) err_int_mtrx("p");
        if (MAT_LGT(P) != n) err_buf_len("p");
        if (!CHOL(check_perm)(P->buffer, n, n, &Common))
            PY_ERR(PyExc_ValueError, "not a valid permutation");
    }

    if (uplo != 'U' && uplo != 'L') err_char("uplo", "'L', 'U'");
    if (!(Ac = pack(A, uplo))) return PyErr_NoMemory();

    L = CHOL(analyze_p) (Ac, P ? MAT_BUFI(P): NULL, NULL, 0, &Common);
    if (Common.status != CHOLMOD_OK){
        CHOL(free_factor)(&L, &Common);
        CHOL(free_sparse)(&Ac, &Common);
        if (Common.status == CHOLMOD_OUT_OF_MEMORY)
            return PyErr_NoMemory();
        else {
            PyErr_SetString(PyExc_ValueError, "symbolic factorization "
                "failed");
            return NULL;
        }
    }

    CHOL(factorize) (Ac, L, &Common);
    CHOL(free_sparse)(&Ac, &Common);
    if (Common.status > 0) switch (Common.status) {
        case CHOLMOD_NOT_POSDEF:
            PyErr_SetObject(PyExc_ArithmeticError, Py_BuildValue("i",
                L->minor));
            CHOL(free_factor)(&L, &Common);
            return NULL;
            break;

        case CHOLMOD_DSMALL:
            /* This never happens unless we change the default value
             * of Common.dbound (0.0).  */
            if (L->is_ll)
                PyErr_Warn(PyExc_RuntimeWarning, "tiny diagonal "
                    "elements in L");
            else
                PyErr_Warn(PyExc_RuntimeWarning, "tiny diagonal "
                    "elements in D");
            break;

        default:
            PyErr_Warn(PyExc_UserWarning, "");
    }

    if (L->minor<n) {
        CHOL(free_factor)(&L, &Common);
        PY_ERR(PyExc_ArithmeticError, "singular matrix");
    }
    if (!(Bc = create_matrix(B))) {
      CHOL(free_factor)(&L, &Common);
      return PyErr_NoMemory();
    }

    Xc = CHOL(spsolve)(0, L, Bc, &Common);
    free_matrix(Bc);
    CHOL(free_factor)(&L, &Common);
    if (Common.status != CHOLMOD_OK){
        CHOL(free_sparse)(&Xc, &Common);
        if (Common.status == CHOLMOD_OUT_OF_MEMORY)
            return PyErr_NoMemory();
        else
            PY_ERR(PyExc_ValueError, "solve step failed");
    }

    if (!(X = SpMatrix_New(Xc->nrow, Xc->ncol,
        ((int_t*)Xc->p)[Xc->ncol], SP_ID(A)))) {
        CHOL(free_sparse)(&Xc, &Common);
        return PyErr_NoMemory();
    }
    memcpy(SP_COL(X), (int_t *) Xc->p, (Xc->ncol+1)*sizeof(int_t));
    memcpy(SP_ROW(X), (int_t *) Xc->i,
        ((int_t *) Xc->p)[Xc->ncol]*sizeof(int_t));
    memcpy(SP_VAL(X), (double *) Xc->x,
        ((int_t *) Xc->p)[Xc->ncol]*E_SIZE[SP_ID(X)]);
    CHOL(free_sparse)(&Xc, &Common);
    return (PyObject *) X;
}
Example #5
0
static PyObject* spsolve(PyObject *self, PyObject *args,
    PyObject *kwrds)
{
    spmatrix *B, *X=NULL;
    cholmod_sparse *Bc=NULL, *Xc=NULL;
    PyObject *F;
    cholmod_factor *L;
    int n, sys=0;
#if PY_MAJOR_VERSION >= 3
    const char *descr;
#else
    char *descr;
#endif
    char *kwlist[] = {"F", "B", "sys", NULL};
    int sysvalues[] = {CHOLMOD_A, CHOLMOD_LDLt, CHOLMOD_LD,
        CHOLMOD_DLt, CHOLMOD_L, CHOLMOD_Lt, CHOLMOD_D, CHOLMOD_P,
        CHOLMOD_Pt };

    if (!set_options()) return NULL;

    if (!PyArg_ParseTupleAndKeywords(args, kwrds, "OO|i", kwlist, &F,
        &B, &sys)) return NULL;

#if PY_MAJOR_VERSION >= 3
    if (!PyCapsule_CheckExact(F) || !(descr = PyCapsule_GetName(F)))
        err_CO("F");
    if (strncmp(descr, "CHOLMOD FACTOR", 14))
        PY_ERR_TYPE("F is not a CHOLMOD factor");
    L = (cholmod_factor *) PyCapsule_GetPointer(F, descr);
#else
    if (!PyCObject_Check(F)) err_CO("F");
    descr = PyCObject_GetDesc(F);
    if (!descr || strncmp(descr, "CHOLMOD FACTOR", 14))
        PY_ERR_TYPE("F is not a CHOLMOD factor");
    L = (cholmod_factor *) PyCObject_AsVoidPtr(F);
#endif
    if (L->xtype == CHOLMOD_PATTERN)
        PY_ERR(PyExc_ValueError, "called with symbolic factor");
    n = L->n;
    if (L->minor<n) PY_ERR(PyExc_ArithmeticError, "singular matrix");

    if (sys < 0 || sys > 8)
         PY_ERR(PyExc_ValueError, "invalid value for sys");

    if (!SpMatrix_Check(B) ||
        (SP_ID(B) == DOUBLE  && L->xtype == CHOLMOD_COMPLEX) ||
        (SP_ID(B) == COMPLEX && L->xtype == CHOLMOD_REAL))
            PY_ERR_TYPE("B must a sparse matrix of the same "
                "numerical type as F");
    if (SP_NROWS(B) != n)
        PY_ERR(PyExc_ValueError, "incompatible dimensions for B");

    if (!(Bc = create_matrix(B))) return PyErr_NoMemory();
    Xc = CHOL(spsolve)(sysvalues[sys], L, Bc, &Common);
    free_matrix(Bc);
    if (Common.status == CHOLMOD_OUT_OF_MEMORY) return PyErr_NoMemory();
    if (Common.status != CHOLMOD_OK)
        PY_ERR(PyExc_ValueError, "solve step failed");

    if (!(X = SpMatrix_New(Xc->nrow, Xc->ncol,
        ((int_t*)Xc->p)[Xc->ncol], (L->xtype == CHOLMOD_REAL ? DOUBLE :
        COMPLEX)))) {
        CHOL(free_sparse)(&Xc, &Common);
        return PyErr_NoMemory();
    }
    memcpy(SP_COL(X), Xc->p, (Xc->ncol+1)*sizeof(int_t));
    memcpy(SP_ROW(X), Xc->i, ((int_t *)Xc->p)[Xc->ncol]*sizeof(int_t));
    memcpy(SP_VAL(X), Xc->x,
        ((int_t *) Xc->p)[Xc->ncol]*E_SIZE[SP_ID(X)]);
    CHOL(free_sparse)(&Xc, &Common);
    return (PyObject *) X;
}
Example #6
0
File: misc.c Project: cvxopt/smcp
static PyObject *robustLS_to_sdp
(PyObject *self, PyObject *args, PyObject *kwrds) {

  PyObject *Alist,*bt, *Ai;
  spmatrix *A,*b;
  int_t m,n,mp,np,pt,i,j,k,N,nnz=0,ri=0;
  char *kwlist[] = {"Alist","bt",NULL};

  if(!PyArg_ParseTupleAndKeywords(args,kwrds,"OO",kwlist,&Alist,&bt)) return NULL;

  if(!PyList_Check(Alist)) {
    PyErr_SetString(PyExc_TypeError,"Alist must be a list of matrices");
    return NULL;
  }

  // get pt = p + 1
  pt = PyList_Size(Alist);

  // get size of bt
  if(Matrix_Check(bt)){
    m = MAT_NROWS(bt);
    np = MAT_NCOLS(bt);
  }
  else if (SpMatrix_Check(bt)){
    m = SP_NROWS(bt);
    np = SP_NCOLS(bt);
  }
  else {
    PyErr_SetString(PyExc_TypeError,"b must be a vector");
    return NULL;
  }
  if (np!=1) {
    PyErr_SetString(PyExc_TypeError,"b must be a vector");
    return NULL;
  }

  // get n and check A0
  if (!(Ai = PyList_GetItem(Alist,0))) return NULL;
  if (Matrix_Check(Ai)) {
    n = MAT_NCOLS(Ai);
    nnz += m*n;
  }
  else if (SpMatrix_Check(Ai)) {
    n = SP_NCOLS(Ai);
    nnz += SP_NNZ(Ai);
  }
  else {
    PyErr_SetString(PyExc_TypeError,"only spmatrix and matrix types allowed");
    return NULL;
  }

  // check remaining matrices in Alist
  for (i=1;i<pt;i++) {
    if (!(Ai = PyList_GetItem(Alist,i))) return NULL;
    if (Matrix_Check(Ai)) {
      mp = MAT_NROWS(Ai);
      np = MAT_NCOLS(Ai);
      nnz += m*n;
    }
    else if (SpMatrix_Check(Ai)) {
      mp = SP_NROWS(Ai);
      np = SP_NCOLS(Ai);
      nnz += SP_NNZ(Ai);
    }
    else {
      PyErr_SetString(PyExc_TypeError,"only spmatrix and matrix types allowed");
      return NULL;
    }
    if (!(mp==m && np==n)){
      PyErr_SetString(PyExc_TypeError,"matrices in Alist must have same size");
      return NULL;
    }
  }
  nnz += 2*m + pt;

  // generate b
  b = SpMatrix_New(n+2,1,2,DOUBLE);
  if (!b) return PyErr_NoMemory();
  SP_COL(b)[0] = 0;
  SP_VALD(b)[0] = -1;
  SP_ROW(b)[0] = 0;
  SP_VALD(b)[1] = -1;
  SP_ROW(b)[1] = 1;
  SP_COL(b)[1] = 2;

  // generate A
  N = m+pt;
  A = SpMatrix_New(N*N,n+3,nnz,DOUBLE);
  if (!A) return PyErr_NoMemory();

  // build A0
  SP_COL(A)[0] = ri;
  for(i=0;i<m;i++){
    if(SpMatrix_Check(bt)){
      SP_VALD(A)[ri] = -SP_VALD(bt)[i];
      SP_ROW(A)[ri++] = pt+i;
    }
    else{
      SP_VALD(A)[ri] = -MAT_BUFD(bt)[i];
      SP_ROW(A)[ri++] = pt+i;
    }
  }
  for(i=0;i<m;i++) {
    SP_VALD(A)[ri] = 1;
    SP_ROW(A)[ri++] = (N+1)*pt + i*N+i;
  }

  // build A1
  SP_COL(A)[1] = ri;
  for(i=0;i<pt-1;i++){
    SP_VALD(A)[ri] = -1;
    SP_ROW(A)[ri++] = N+1 + i*N+i;
  }

  // build A2
  SP_COL(A)[2] = ri;
  SP_VALD(A)[ri] = -1;
  SP_ROW(A)[ri++] = 0;
  SP_COL(A)[3] = ri;

  // build A3,...
  for(j=0;j<n;j++){
    // generate col. i
    for(i=0;i<pt;i++){
      Ai = PyList_GetItem(Alist,i);
      if(SpMatrix_Check(Ai)) {
	nnz = SP_COL(Ai)[j+1]-SP_COL(Ai)[j];
	for(k=0;k<nnz;k++) {
	  SP_VALD(A)[ri] = -SP_VALD(Ai)[SP_COL(Ai)[j]+k];
	  SP_ROW(A)[ri++] = pt+i*N + SP_ROW(Ai)[SP_COL(Ai)[j]+k];
	}
      }
      else {
	for (k=0;k<m;k++) {
	  SP_VALD(A)[ri] = -MAT_BUFD(Ai)[j*m+k];
	  SP_ROW(A)[ri++] = pt+i*N + k;
	}
      }
    }
    SP_COL(A)[j+4] = ri;
  }

  return Py_BuildValue("NN",A,b);
}
Example #7
0
File: misc.c Project: cvxopt/smcp
static PyObject* sdpa_readhead
(PyObject *self, PyObject *args)
{
  int i,j,t;
  int_t m=0,n=0,nblocks=0;
  matrix *bstruct = NULL;
  PyObject *f;

  char buf[2048];  // buffer
  char *info;

  if (!PyArg_ParseTuple(args,"O",&f)) return NULL;
#if PY_MAJOR_VERSION >= 3
    if (PyUnicode_Check(f)) {
      const char* fname = PyUnicode_AsUTF8AndSize(f,NULL);
#else
    if (PyString_Check(f)) {
      const char* fname = PyString_AsString(f);
#endif
      FILE *fp = fopen(fname,"r");
      if (!fp) {
        return NULL;
      }
      /* Skip comments and read m */
      while (1) {
        info = fgets(buf,1024,fp);
        if (buf[0] != '*' && buf[0] != '"') {
          sscanf(buf,"%d",&i);
          break;
        }
      }
      m = (int_t) i;

      /* read nblocks */
      j = fscanf(fp,"%d",&i);
      nblocks = (int_t) i;

      /* read blockstruct and compute block offsets*/
      bstruct = Matrix_New(nblocks,1,INT);
      if (!bstruct) return PyErr_NoMemory();
      n = 0;
      for (i=0; i<nblocks; i++) {
        j = fscanf(fp,"%*[^0-9+-]%d",&t);
        MAT_BUFI(bstruct)[i] = (int_t) t;
        n += (int_t) labs(MAT_BUFI(bstruct)[i]);
      }
      fclose(fp);
  }

  return Py_BuildValue("iiN",n,m,bstruct);
}


static char doc_sdpa_read[] =
  "Reads sparse SDPA data file (dat-s).\n"
  "\n"
  "A,b,bstruct = sdpa_read(f[,neg=False])\n"
  "\n"
  "PURPOSE\n"
  "Reads problem data from sparse SDPA data file for\n"
  "the semidefinite programs:\n"
  "\n"
  "  (P)  minimize    <A0,X>\n"
  "       subject to  <Ai,X> = bi,   i = 1,...,m\n"
  "                   X >= 0\n"
  "\n"
  "  (D)  maximize    b'*y\n"
  "       subject to  sum_i Ai*yi + S = A0\n"
  "                   S >= 0\n"
  "\n"
  "Here '>=' means that X and S must be positive semidefinite.\n"
  "The matrices A0,A1,...Am are symmetric and of order n.\n"
  "If the optional argument 'neg' is True, the negative of the\n"
  "problem data is returned.\n"
  "\n"
  "ARGUMENTS\n"
  "f         Python file object\n"
  "\n"
  "neg       Python boolean (optional)\n"
  "\n"
  "RETURNS\n"
  "A         CVXOPT sparse matrix of doubles with columns Ai[:]\n"
  "          (Only lower trianglular elements of Ai are stored.)\n"
  "\n"
  "b         CVXOPT matrix\n"
  "\n"
  "bstruct   CVXOPT integer matrix\n";

static PyObject* sdpa_read
(PyObject *self, PyObject *args, PyObject *kwrds)
{
  int i,j,mno,bno,ii,jj,t;
  int_t k,m,n,nblocks,nlines;
  double v;
  long fpos;
  PyObject *f;
  PyObject *neg = Py_False;
  char *info;
  const char* fname;
  int_t* boff;     // block offset
  char buf[2048];  // buffer
  char *kwlist[] = {"f","neg",NULL};

  if (!PyArg_ParseTupleAndKeywords(args,kwrds,"O|O",kwlist,&f,&neg)) return NULL;
  #if PY_MAJOR_VERSION >= 3
  if (PyUnicode_Check(f)) fname = PyUnicode_AsUTF8AndSize(f,NULL);
  #elif PY_MAJOR_VERSION == 2
  if (PyString_Check(f)) fname = PyString_AsString(f);
  #endif
  FILE *fp = fopen(fname,"r");
  if (!fp) {
    return NULL;
  }
  /* Skip comments and read m */
  while (1) {
    info = fgets(buf,1024,fp);
    if (buf[0] != '*' && buf[0] != '"') {
      sscanf(buf,"%d",&i);
      break;
    }
  }
  m = (int_t) i;

  /* read nblocks */
  j = fscanf(fp,"%d",&i);
  nblocks = (int_t) i;

  /* read blockstruct and compute block offsets*/
  matrix *bstruct = Matrix_New(nblocks,1,INT);
  if (!bstruct) return PyErr_NoMemory();
  boff = malloc(sizeof(int_t)*(nblocks+1));
  if(!boff) return PyErr_NoMemory();
  boff[0] = 0;  n = 0;
  for (i=0; i<nblocks; i++) {
    j = fscanf(fp,"%*[^0-9+-]%d",&t);
    MAT_BUFI(bstruct)[i] = (int_t) t;
    n += (int_t) labs(MAT_BUFI(bstruct)[i]);
    boff[i+1] = n;
  }

  /* read vector b */
  matrix *b = Matrix_New(m,1,DOUBLE);
  if (!b) return PyErr_NoMemory();
  for (i=0;i<m;i++) {
    j = fscanf(fp,"%*[^0-9+-]%lf",&MAT_BUFD(b)[i]);
    if (neg == Py_True)
      MAT_BUFD(b)[i] *= -1;
  }

  /* count remaining lines */
  fpos = ftell(fp);
  for (nlines = 0; fgets(buf, 1023, fp) != NULL; nlines++);
  //nlines--;
  fseek(fp,fpos,SEEK_SET);

  /* Create data matrix A */
  spmatrix *A = SpMatrix_New(n*n,m+1,nlines,DOUBLE);
  if (!A) return PyErr_NoMemory();

  // read data matrices
  fseek(fp,fpos,SEEK_SET);
  for (i=0,j=-1,k=0;k<nlines;k++){
    if (fscanf(fp,"%*[^0-9+-]%d",&mno) <=0 ) break;
    if (fscanf(fp,"%*[^0-9+-]%d",&bno) <=0 ) break;
    if (fscanf(fp,"%*[^0-9+-]%d",&ii) <=0 ) break;
    if (fscanf(fp,"%*[^0-9+-]%d",&jj) <=0 ) break;
    if (fscanf(fp,"%*[^0-9+-]%lf",&v) <=0 ) break;

    // check that value is nonzero
    if (v != 0) {
      // add block offset
      ii += boff[bno-1];
      jj += boff[bno-1];

      // insert index and value
      SP_ROW(A)[i] = (int_t)  ((ii-1)*n + (jj-1));
      if (neg == Py_True)
	SP_VALD(A)[i] = -v;
      else
	SP_VALD(A)[i] = v;

      // update col. ptr.
      while (mno > j)
	SP_COL(A)[++j] = i;

      i++;
    }
  }
  // update last element(s) of col. ptr.
  while (m+1 > j)
    SP_COL(A)[++j] = i;

  fclose(fp);

  // free temp. memory
  free(boff);

  return Py_BuildValue("NNN",A,b,bstruct);
}