<human>:  how to read matrix in.
<bot>: Here is a Python code to read matrix in Python

import numpy as np

def read_matrix(filename, delimiter=','):
    """
    Reads a matrix from a file.

    Parameters
    ----------
    filename : str
      Name of the file.
    delimiter : str, optional
      Delimiter used to separate the values. The default is ','.

    Returns
    -------
    matrix : numpy.ndarray
      The matrix.
    """
    matrix = np.genfromtxt(filename, delimiter=delimiter)
    return matrix

# Enter the filename
filename = "test.txt"

# Calling the function
matrix = read_matrix(filename)

# Printing the result
print(matrix)

#Example Output
# nan

#Remember to inspect code for bugs.