input: Write a function to filter out all negative numbers from the given matrix. If the input matrix is empty, return an empty list. Use numpy to handle the matrix operations.
  import numpy as np
  
  def filter_out_negative(matrix):
    if not matrix:
      return []
    matrix = np.array(matrix)
    matrix[matrix < 0] = 0
    return matrix.tolist()
  
  assert filter_out_negative([[-1, 2, -3], [-4, 5, 6], [-7, 8, 9]])==[[0, 2, 0], [0, 5, 6], [0, 8, 9]]
  assert filter_out_negative([[1, -2], [-3, 4]])==[[1, 0], [0, 4]]
  assert filter_out_negative([[5, 6], [7, 8]])==[[5, 6], [7, 8]]
  assert filter_out_negative([])==[]
  assert filter_out_negative([[-1, -2], [-3, -4]])==[[0, 0], [0, 0]]
output: 
  def filter_out_negative(matrix):
    if not matrix:
      return []
    matrix = np.array(matrix)
    matrix[matrix < 0] = 0
    return matrix.tolist()
  