How to return numpy.array using python in simulink

I built a neural network controller in python, and want to control a simulink model using the python function. The input and output of my python function are 'numpy.array'. The output shape is [4, 1].

I used a 'matlab function' to call the python function in simulink. The code of the matlab function is as follows:

function [u1, u2, u3, u4] = fcn(data_in)
coder.extrinsic('py.controller.multi_output')
out = 0;
out = py.controller.multi_output(data_in);
u1 = out(1);
u2 = out(2);
u3 = out(3);
u4 = out(4);

The 'controller' is the python code and the 'multi_output' is the name of my python function.

The 'py.controller.multi_output(data_in)' works well in matlab and returns ndarray. I can transform the ndarray to double.

But it does not work in simulink:

An error occurred while running the simulation and the simulation was terminated
Caused by:
MATLAB expression '<output of py.controller.multi_output>' is not numeric.

Why does this error occurs?

[hao wu]

Create a separate MATLAB function (myfcn.m) that calls "py.controller.multi_output" and performs the conversion between MATLAB double arrays and the ndarrays for Python.

It works.