How to search for a condition in all index in a row

Hello,

I have quite a big matrix where I need it to find the next number in a row smaller than 45.20

e.g.

0.7 45.03 45.15 44 44

0.4 45.20 44 44 44

0.5 45.20 44.3 44 44

0.38 45.20 44.9 44 44

The bold marking i is our point of interest:

What I need is: 0,7 is added to 45,03, and if ans i larger than 45,20, the surplus is added to 45,15. If this again results in a surplus, this is added to 44 (i-1,j+1) and so forth.

The correct answer should be:

0.7 45.03 45.15 44 44

0.4 45.20 45.20 44.48 44

0.5 45.20 44.20 44.88 44

0.38 45.20 45.2 45.2 44.18

Since I have a large matrix I cannot just use (which is my currently code)

if A(i,j-1) == 45.20 && A(i-1,1) + A(i-1,j-1) > 45.20 
A(i,j) = A(i-1,1) + A(i-1,j-1) - 45.20 + A(i-1,j);
   if A(i,j) > 45.20
     A(i,j+1) = A(i,j+1) - 45.20 + A(i-1,j+1);
    A(i,j) = 45.20;
end
end

because it gets the wrong answer in colums later on. I therefore need it to search for the next value smaller than 45.20 and then fill it up.

[KSSV]

Read about logical indexing. You need not to use a loop. At a stretch you can get all the indices which are less than 45.20

idx = A(:,2)<=45.20 ;

Answer 1

[Parag Jhunjhunwala]

Hi @Helena Hjørringgaard,

Below is the sample code to address the problem you are facing.The approach to the implementation is covered in comments in the code.

% Traverse the rows of the matrix from top to bottom excluding the last row
for i=1:n-1
    % Initialize the remainder value as the value at first column of the ith row
    rem=A(i,1);
    % Traverse the columns of the ith row starting from the 2nd column
    for j=2:m
        % If the remainder becomes 0 move on to the next row iteration
        if(~rem)
            break;
        end
        % if the sum of remainder and the value at ith row and jth column is greater than 45.2(stored as
        % val),assign val to the element just below it and update the remainder otherwise assign the sum
        % to the element just below it and move on to the next row iteration(by making remainder 0)
        if(rem+A(i,j) >= val)
            A(i+1,j)=val;
            rem=rem+A(i,j)-val;
        else
            A(i+1,j)=rem+A(i,j);
            rem=0;
        end
    end
end