def get_zero_columns(matrix):
    """ Returns a list of the columns which are all 0 """
    rows = matrix.shape[0]
    columns = matrix.shape[1]

    result = []
    for j in range(columns):
        is_zero_column = True
        for i in range(rows):
            is_zero_column = is_zero_column and matrix[i, j] == 0.0
        result.append(is_zero_column)

    return result