matlab conversion issue

function [out1] = simple_waiting(input)
% The input will be a directory name
% out1 is an array of parsed patient info
% (didn't have to make proper parser- just got the answers in this file)

clear
clc
close all

data_matrix =  [1,735724.291666667,735724.322916667,735724.343750000,5;2,735724.331250000,735724.340277778,735724.371527778,18];

%edited to have both wait: 
%data_matrix =
%[1,735724.291666667,735724.322916667,735724.343750000,5;2,735724.322916667,735724.340277778,735724.371527778,18];

% get the problem again even just by repeating that last row: 
%data_matrix =  [1,735724.291666667,735724.322916667,735724.343750000,5;2,735724.331250000,735724.340277778,735724.371527778,18;2,735724.331250000,735724.340277778,735724.371527778,18]

patient_queue = [];
highest_wait_num = 0;
[rows, columns] = size(data_matrix);

for i = 1:rows
    this_row_arrival = datetime (data_matrix(i, 2), 'ConvertFrom', 'datenum');
    this_row_exam_start = datetime (data_matrix(i, 3), 'ConvertFrom', 'datenum');
    now = this_row_arrival;  %making a copy called 'now' so it's clear below
    %now = datetime(this_row_arrival, 'InputFormat', 'dd-MMM-yyyy HH:mm:ss')
    
    % check patient queue: if anyone left in the meantime, remove them
    for j = 1:length(patient_queue)
        %if patient_queue{j} < this_row_arrival %Comparison is not defined between double and datetime arrays.
        if patient_queue{j} < now
        %if true
            patient_queue(j) = [];
        end
    end

    % if new patient isn't seen immediately (tb > ta), add tb to the queue
    if this_row_exam_start > this_row_arrival
        patient_queue{end+1} = this_row_exam_start;
    end
    
    % get the current queue size
    patient_queue_non_zero = (~cellfun('isempty',patient_queue));  
    indices = find(patient_queue_non_zero); 
    current_queue_count = length(indices);
   
    % if the current queue size beats the highest we've seen, update it
    if current_queue_count > highest_wait_num
       highest_wait_num = current_queue_count;
    end
   
end

patient_queue{j}
highest_wait_num

end