How to change values from negative to positive and vicer versa in a loop

Dear Everyone;

I have created a for loop to compute certain values. Within the loop if Mw, Mx, My and Mz comes out of as a postive number I want to change it to a negative; and if Mw, Mx, My and Mz comes out of as a negative number I want to change it to a positive.

I have tried to do this with "If Statements", but the set of values come out as all positive or all negative.

Here is my code:

clear, clc, close all

% Distribution factor
DF = [0.4444 0.5556 0.5714 0.4286];

% Starting bending moments
    M1 = (-25 + 20)*DF(1);
    M2 = (-25 + 20)*DF(2);
    M3 = (-20 + 4.67)*DF(3);
    M4 = (-20 + 4.67)*DF(4);

for i = 1:8
    % carry over
    cf1 = M1/2; 
    cf2 = M2/2;
    cf3 = M3/2;

% First distribution
    Mw(i) = (0 + cf3)*DF(1)
    Mx(i) = (0 + cf3)*DF(2)
    My(i) = (0 + cf2)*DF(3)
    Mz(i) = (0 + cf2)*DF(4)
    
% If Mw, Mx, My and Mz is positive change to a negative value
   if Mw(i) > 0
        Mw(i) = -(Mw(i))
 % If Mw, Mx, My and Mz is negative change to a positive value
    elseif Mw(i) < 0
        Mw(i) = abs(Mw(i))
    end

    M1 = Mw(i);
    M2 = Mx(i);
    M3 = My(i);
    M4 = Mz(i);

As you can see I have only attempted this with Mw. This is just to practise. Once I get the correct results I will include Mx, My and Mz.

Can someone help please?

[Torsten]

Simply set

Mw(i) = -Mw(i)

Answer 1

[Voss]

clear, clc, close all

% Distribution factor
DF = [0.4444 0.5556 0.5714 0.4286];

% Starting bending moments
M1 = (-25 + 20)*DF(1);
M2 = (-25 + 20)*DF(2);
M3 = (-20 + 4.67)*DF(3);
M4 = (-20 + 4.67)*DF(4);

for i = 1:8
    % carry over
    cf1 = M1/2; 
    cf2 = M2/2;
    cf3 = M3/2;

    % First distribution
    Mw(i) = -(0 + cf3)*DF(1);
    Mx(i) = -(0 + cf3)*DF(2);
    My(i) = -(0 + cf2)*DF(3);
    Mz(i) = -(0 + cf2)*DF(4);
    
    M1 = Mw(i);
    M2 = Mx(i);
    M3 = My(i);
    M4 = Mz(i);

end

Mw

Mw = 1×8

1.9464 -0.1764 0.1545 -0.0140 0.0123 -0.0011 0.0010 -0.0001

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Mx

Mx = 1×8

2.4334 -0.2205 0.1931 -0.0175 0.0153 -0.0014 0.0012 -0.0001

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My

My = 1×8

0.7937 -0.6952 0.0630 -0.0552 0.0050 -0.0044 0.0004 -0.0003

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Mz

Mz = 1×8

0.5953 -0.5215 0.0472 -0.0414 0.0038 -0.0033 0.0003 -0.0003

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