Function execute_real_backward

numpy/fft/_pocketfft.c:2283–2324

    return (PyObject *)ret;
}
static PyObject *
execute_real_backward(PyObject *a1, double fct)
{
    rfft_plan plan=NULL;
    PyArrayObject *data = (PyArrayObject *)PyArray_FromAny(a1,
            PyArray_DescrFromType(NPY_CDOUBLE), 1, 0,
            NPY_ARRAY_DEFAULT | NPY_ARRAY_ENSUREARRAY | NPY_ARRAY_FORCECAST,
            NULL);
    if (!data) return NULL;
    int npts = PyArray_DIM(data, PyArray_NDIM(data) - 1);
    PyArrayObject *ret = (PyArrayObject *)PyArray_Empty(PyArray_NDIM(data),
            PyArray_DIMS(data), PyArray_DescrFromType(NPY_DOUBLE), 0);
    int fail = 0;
    if (!ret) fail=1;
    if (!fail) {
      int nrepeats = PyArray_SIZE(ret)/npts;
      double *rptr = (double *)PyArray_DATA(ret),
             *dptr = (double *)PyArray_DATA(data);

      Py_BEGIN_ALLOW_THREADS;
      plan = make_rfft_plan(npts);
      if (!plan) fail=1;
      if (!fail) {
        for (int i = 0; i < nrepeats; i++) {
          memcpy((char *)(rptr + 1), (dptr + 2), (npts - 1)*sizeof(double));
          rptr[0] = dptr[0];
          if (rfft_backward(plan, rptr, fct)!=0) {fail=1; break;}
          rptr += npts;
          dptr += npts*2;
        }
      }
      if (plan) destroy_rfft_plan(plan);
      Py_END_ALLOW_THREADS;
    }
    if (fail) {
      Py_XDECREF(data);
      Py_XDECREF(ret);
      return PyErr_NoMemory();
    }
    Py_DECREF(data);
    return (PyObject *)ret;
}

static PyObject *
execute_real(PyObject *a1, int is_forward, double fct)