How to compare two columns of every row and display them?

TASK 1: So I have a simple vector and I needed to compare if first column is greater than the second column.

N = [1042, 713, 4, 42]

N = 1×4

1042 713 4 42

N(1); , N(2);
if N(1) > N(2)
   disp("increasing");  % if column 1 is greater it is increasing
else
   disp("decreasing");  % if column 2 is greater it is decreasing
end

increasing

TASK 2: This time I need to calculate the sum of the first 3 columns and also print the last column. Repeating each row. Now say the vector has become a 4 x 4.

M = [1042 713 4 42; 30 48 0 12; 4 160 12 1; 1 111 2 0]

M = 4×4

1042 713 4 42 30 48 0 12 4 160 12 1 1 111 2 0

extra = M(:, 4);
sum = M(:, 1) + M(:, 2) + M(:, 3);
% I want to print this in a format of:
fprintf('Sum of values: %.0f, extra value: %.0f\n', [sum(:),extra(:)].');

Sum of values: 1759, extra value: 42
Sum of values: 78, extra value: 12
Sum of values: 176, extra value: 1
Sum of values: 114, extra value: 0

TASK 3: Now I need to extend Task 2 by repeating Task 1 of comparing the first column to the second column of each row.

The format will be like this: Sum of values: "val1", extra value: "val2" increasing (*or decreasing)

What I've came up with is this and so far it hasn't been working since it prints decreasing for every row even tho first one is increasing.

A = M(:, 1);
B = M(:, 2);
disp("The cases are: ");

The cases are: 

M;
chan = M(:, 4);
for sum3 = M(:, 1) + M(:, 2) + M(:, 3);
    if A > B
        %    disp("increasing");
        fprintf('Sum of values: %.0f, extra value: %.0f increasing\n'...
            ,[sum3(:),chan(:)].');
    else
        %    disp("decreasing");
        fprintf('Sum of values: %.0f, extra value: %.0f decreasing\n'...
            ,[sum3(:),chan(:)].');
    end
end

Sum of values: 1759, extra value: 42 decreasing
Sum of values: 78, extra value: 12 decreasing
Sum of values: 176, extra value: 1 decreasing
Sum of values: 114, extra value: 0 decreasing

How to simplify or code this properly? Thank you :)

Answer 1

[DGM]

Well, this is what I did.

% PART 2
M = [1042 713 4 42; 30 48 0 12; 4 160 12 1; 1 111 2 0]

M = 4×4

1042 713 4 42 30 48 0 12 4 160 12 1 1 111 2 0

extra = M(:, 4);
sum3col = sum(M(:,1:3),2); % don't overload sum()
fprintf('Sum of values: %.0f, extra value: %.0f\n', [sum3col(:),extra(:)].');

Sum of values: 1759, extra value: 42
Sum of values: 78, extra value: 12
Sum of values: 176, extra value: 1
Sum of values: 114, extra value: 0

% PART 3
deltastr = {'decreasing','unchanged','increasing'};
deltastridx = sign(diff(M(:,1:2),1,2))+2;

% loop can be avoided, but it gets messy with mixed array types
for r = 1:size(M,1)
    fprintf('Sum of values: %.0f, extra value: %.0f, %s\n', ...
        sum3col(r),extra(r),deltastr{deltastridx(r)});
end

Sum of values: 1759, extra value: 42, decreasing
Sum of values: 78, extra value: 12, increasing
Sum of values: 176, extra value: 1, increasing
Sum of values: 114, extra value: 0, increasing

The loop can be avoided, but the mixed numeric/cell array inputs make it a mess that makes for at least as much clutter.

[Daven Artajo]

Part 2 was great thanks for simplifying it. Part 3 however, the output for "increasing/decreasing" are opposite of what it should be i.e. first row should be "*increasing*" and the next 3 rows are "*decreasing*". Do I just swap the strings around for deltastr?

[DGM]

I was working on the assumption that each row represents a sequence from left to right (in the order of their subscripts). Under that assumption, [1042 713] is a decreasing series.

If you want to assume a different convention, then yeah. You can either just flip deltastr()

deltastr = {'increasing','unchanged','decreasing'}; 

or you can invert the index vector.

deltastridx = 2-sign(diff(M(:,1:2),1,2));

[Daven Artajo]

The assumption is that in Part 2 4x4 vector, if the first column is greater than the second then it is increasing [1042 > 713], else if not then it is decreasing [30 < 48]. Anyways, thank you very much for the answer, this was the question I got stompt on.