Hi, I've written some C code for number crunching that uses the following structure for simulating 2-dimensional arrays (i.e. matrices): typedef struct { double **aa; int nrows; int ncols; } Array2d; In order to read these C arrays in Python+Numeric and vice versa, I've written some wrapping code, but I'm not so sure it's correct. In particular I'm concerned in memory leakage, I don't know if I've understood correctly how PyArray_FromDimsAndData works and if I've choose the best way to solve the problem. My code follows. Thanks for help! Andrea. C --> Python ============ static PyObject *Array2d_2_PyArrayObject(Array2d *input) { int ndims[2]; PyArrayObject *result; if (!input) return NULL; ndims[0] = input->nrows; ndims[1] = input->ncols; result = (PyArrayObject *) PyArray_FromDimsAndData(2, ndims, PyArray_DOUBLE, (char *) input->aa[0]); free(input->aa); free(input); return PyArray_Return(result); } Python --> C ============ static Array2d *PyList_2_Array2d(PyObject *input) { Array2d *result; if (!PySequence_Check(input)) { PyErr_SetString(PyExc_TypeError,"Expected a sequence"); return NULL; } result = (Array2d *) malloc(sizeof(Array2d)); PY_CHECK_ALLOC(result); if (PyArray_As2D((PyObject **) &input, (char ***) &(result->aa), &(result->nrows), &(result->ncols), PyArray_DOUBLE) != 0) { PyErr_SetString(PyExc_MemoryError,"No heap space for data"); return NULL; } return result; } --- Andrea Riciputi "Science is like sex: sometimes something useful comes out, but that is not the reason we are doing it" -- (Richard Feynman)