Function _find_array_prepare

numpy/core/src/umath/ufunc_object.c:294–332

* This function analyzes the input arguments * and determines an appropriate __array_prepare__ function to call * for the outputs. * * If an output argument is provided, then it is prepped * with its own __array_prepare__ not with the one determined by * the input arguments. * * if the provided output argument is already an ndarray, * the prepping function is None (which means no prepping

 * should just have PyArray_Return called.
 */
static void
_find_array_prepare(ufunc_full_args args,
                    PyObject **output_prep, int nout)
{
    int i;
    PyObject *prep;

    /*
     * Determine the prepping function given by the input arrays
     * (could be NULL).
     */
    prep = _find_array_method(args.in, npy_um_str_array_prepare);
    /*
     * For all the output arrays decide what to do.
     *
     * 1) Use the prep function determined from the input arrays
     * This is the default if the output array is not
     * passed in.
     *
     * 2) Use the __array_prepare__ method of the output object.
     * This is special cased for
     * exact ndarray so that no PyArray_Return is
     * done in that case.
     */
    if (args.out == NULL) {
        for (i = 0; i < nout; i++) {
            Py_XINCREF(prep);
            output_prep[i] = prep;
        }
    }
    else {
        for (i = 0; i < nout; i++) {
            output_prep[i] = _get_output_array_method(
                PyTuple_GET_ITEM(args.out, i), npy_um_str_array_prepare, prep);
        }
    }
    Py_XDECREF(prep);
    return;
}

#define NPY_UFUNC_DEFAULT_INPUT_FLAGS \
    NPY_ITER_READONLY | \