How to Evaluate Value In Array in Cell Mode

I want to perform a simple subtraction operation on the value in a cell array that I imported from a text file. See below code. My problem is when I evaluate the value of 'total_time', it spits out some strange array when it should simply be a value. Please help.

%READS FILE AND SAVES DATA INTO MATRIX
filename='data.txt';
[A,B,C]=textread(filename, '%s %s %s');

number_rows=size(A,1);
matrix=cell(number_rows, 3);
matrix(:,:)=[A, B, C];

sampling_rate_current= 10000;
sampling_rate_new=1000;

factor=sampling_rate_current/sampling_rate_new;

% LET X=0 IF EVENLY DIVISIBLE
% LET X=1 IF NOT EVENLY DIVISIBLE
%x=0;
x=1;

%DOWNSIZE DATA IF EVENLY DIVISIBLE
i=1;
j=1;
if x==0
    while i<number_rows
        matrix_down(j,:)=matrix(i,:);
        j=j+1;
        i=i+factor;
    end    
end

%DOWNSIZE DATA IF NOT EVENLY DIVISIBLE
if x==1
    %generate times to be extarcted
       start_time=matrix(1,1);
       end_time=matrix(number_rows,1);
       total_time=end_time{1,1}-start_time{1,1};
       interval=1/sampling_rate_new;
       i=1;
       j=0;
       total=total_time/sampling_rate_new;
       while i<=total
           time_points(i,1)= start_time+j*interval;
           j=j+1;
       end
end

Answer 1

[Sean de Wolski]

Put a break point on that line and inspect the variables.