Function PyArray_Correlate2

numpy/core/src/multiarray/multiarraymodule.c:1389–1458

NUMPY_API * correlate(a1,a2,mode) * * This function computes the usual correlation (correlate(a1, a2) != * correlate(a2, a1), and conjugate the second argument for complex inputs */

 * correlate(a2, a1), and conjugate the second argument for complex inputs
 */
NPY_NO_EXPORT PyObject *
PyArray_Correlate2(PyObject *op1, PyObject *op2, int mode)
{
    PyArrayObject *ap1, *ap2, *ret = NULL;
    int typenum;
    PyArray_Descr *typec;
    int inverted;
    int st;

    typenum = PyArray_ObjectType(op1, NPY_NOTYPE);
    if (typenum == NPY_NOTYPE) {
        return NULL;
    }
    typenum = PyArray_ObjectType(op2, typenum);
    if (typenum == NPY_NOTYPE) {
        return NULL;
    }

    typec = PyArray_DescrFromType(typenum);
    Py_INCREF(typec);
    ap1 = (PyArrayObject *)PyArray_FromAny(op1, typec, 1, 1,
                                        NPY_ARRAY_DEFAULT, NULL);
    if (ap1 == NULL) {
        Py_DECREF(typec);
        return NULL;
    }
    ap2 = (PyArrayObject *)PyArray_FromAny(op2, typec, 1, 1,
                                        NPY_ARRAY_DEFAULT, NULL);
    if (ap2 == NULL) {
        goto clean_ap1;
    }

    if (PyArray_ISCOMPLEX(ap2)) {
        PyArrayObject *cap2;
        cap2 = (PyArrayObject *)PyArray_Conjugate(ap2, NULL);
        if (cap2 == NULL) {
            goto clean_ap2;
        }
        Py_DECREF(ap2);
        ap2 = cap2;
    }

    ret = _pyarray_correlate(ap1, ap2, typenum, mode, &inverted);
    if (ret == NULL) {
        goto clean_ap2;
    }

    /*
     * If we inverted input orders, we need to reverse the output array (i.e.
     * ret = ret[::-1])
     */
    if (inverted) {
        st = _pyarray_revert(ret);
        if (st) {
            goto clean_ret;
        }
    }