Moving a value from one row vector to another row vector

I am trying to move a value from a specified number of columns in a row vector to another specified number of columns in another row vector. I've been using two while loops, one for addition and the other for subtraction. When I use the subtraction loop its seems to stop at one column and give a huge negative number. For the purposes of what I am trying to do I need it to go to the next column if there is a zero (I haven't worked how to do this yet). Anyway here is the code I am currently using,

%
Z = (1:24); % example row vectors
X = linspace(1,500,24);
A = sum(X([17:19])); % quantity that is going to be subtracted from X and added to Z
A1 = A; % value used for second while loop 
B = [1:8 22:23]; % location that A will be distributed to
C = [17:19]; % location that A will be subtracted from
B_increment = A/length(B); % quantity of A to be distributed per a column
ind = 1;
while A >= B_increment
  Z(1, B(ind)) = Z(1, B(ind)) + B_increment;
  A = A - B_increment;
  ind = ind + 1; % move to the next value
  if ind>length(Z(1, B))
        break
  end
end
ind2 = 1; %for second while loop
C_increment = A1/length(C);
while A1 >= C_increment;
  X(1, C(ind2)) = X(1, C(ind2)) - C_increment;
  A1 = A1 - C_increment;
  ind2 = ind2 + 1;
  if ind2>length(X(1, C))
         break
  end
end

The result of the above while loops is the X vector to have [-21, 0, 21] at the specified columns but I want it to be zero for each column. The addition loop appears to be working correctly.

I am writing this script to work with various row vectors of the same dimensions (1x24) but with different numbers.

Am I on the right track and if so is there any advice on how to ensure that none of the values will ever be zero or is there a simpler way to do this?

Answer 1

[Walter Roberson]

With regarding to changing columns:

colnum = 1;
while colnum <= 20
  if data(colnum) >= 3
    data(column) = data(column) - 1;
    colnum = max(1, colnum - 7);
  else
    colnum = colnum + 1;
  end
end

This shows progression by 1 column normally but if a particular value is detected (>=3 in this example) then the column number is changed to something else (7 columns back in this example).

This is not intended to be code to do whatever you are doing: it is code intended to illustrate how you could switch columns.