How to subtract ?

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Arif Hoq
Arif Hoq on 16 Sep 2022
Moved: Stephen23 on 16 Sep 2022
Its just a simple subtraction function in excel. Even It seems very simple in matlab. Still hitting my brain, but ....
A=[0 1 2 3 4 5 6];
B=12;
expected result of C: [11 9 6 2 -3 -9]
hints: 12-1 =11, 11-2=9, 9-3=6, 6-4=2, 2-5=-3, -3-6= -9
  3 Comments
Stephen23
Stephen23 on 16 Sep 2022
Edited: Stephen23 on 16 Sep 2022
"actually this command does not meet my code."
It gives exactly the same result as you request in your question.
And as I show here, using your MAT file data it gives exactly the same output as your more complex loop.

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Accepted Answer

Stephen23
Stephen23 on 16 Sep 2022
Moved: Stephen23 on 16 Sep 2022
The simple MATLAB approach:
S = load("allmat.mat");
M = S.allmat
M = 121×10
0 0 160.0000 80.0000 0 160.0000 80.0000 0 160.0000 80.0000 -1.3713 0 0 0 -0.4571 0 0 0 0 0 -1.6463 0 0 0 -0.5488 0 0 0 0 0 -0.9919 0 0 0 -0.3306 0 0 0 0 0 -0.8804 0 0 0 -0.2935 0 0 0 0 0 2.1362 0 0 0 0.7121 0 0 0 0 0 5.4360 0 0 0 1.8120 0 0 0 0 0 2.1003 0 0 0 0.7001 0 0 0 0 0 -7.7674 0 0 0 -2.5891 0 0 0 0 0 -5.1723 0 0 0 -1.7241 0 0 0 0 0
M(:,6) = M(1,6)-cumsum(M(:,5))
M = 121×10
0 0 160.0000 80.0000 0 160.0000 80.0000 0 160.0000 80.0000 -1.3713 0 0 0 -0.4571 160.4571 0 0 0 0 -1.6463 0 0 0 -0.5488 161.0059 0 0 0 0 -0.9919 0 0 0 -0.3306 161.3365 0 0 0 0 -0.8804 0 0 0 -0.2935 161.6300 0 0 0 0 2.1362 0 0 0 0.7121 160.9179 0 0 0 0 5.4360 0 0 0 1.8120 159.1059 0 0 0 0 2.1003 0 0 0 0.7001 158.4058 0 0 0 0 -7.7674 0 0 0 -2.5891 160.9949 0 0 0 0 -5.1723 0 0 0 -1.7241 162.7190 0 0 0 0

More Answers (3)

Steven Lord
Steven Lord on 16 Sep 2022
A=[0 1 2 3 4 5 6];
B = 12;
C = B-cumsum(A)
C = 1×7
12 11 9 6 2 -3 -9
  1 Comment
Arif Hoq
Arif Hoq on 16 Sep 2022
seems simple and faster. but i can't apply it in my code. I have attached a mat file.
a=load("allmat.mat");
allmat=a.allmat;
batBstorage=allmat(:,6)-cumsum(allmat(:,5));
allmat(:,6)=batBstorage
allmat = 121×10
0 0 160.0000 80.0000 0 160.0000 80.0000 0 160.0000 80.0000 -1.3713 0 0 0 -0.4571 0.4571 0 0 0 0 -1.6463 0 0 0 -0.5488 1.0059 0 0 0 0 -0.9919 0 0 0 -0.3306 1.3365 0 0 0 0 -0.8804 0 0 0 -0.2935 1.6300 0 0 0 0 2.1362 0 0 0 0.7121 0.9179 0 0 0 0 5.4360 0 0 0 1.8120 -0.8941 0 0 0 0 2.1003 0 0 0 0.7001 -1.5942 0 0 0 0 -7.7674 0 0 0 -2.5891 0.9949 0 0 0 0 -5.1723 0 0 0 -1.7241 2.7190 0 0 0 0
but the column 6 would be

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Paul
Paul on 16 Sep 2022
Edited: Paul on 16 Sep 2022
Can do this in a loop
B = 12;
A = [0 1 2 3 4 5 6];
C = 0*A;
C(1) = B(1) - A(1);
for ii = 2:numel(A)
C(ii) = C(ii-1) - A(ii);
end
C = C(2:end)
C = 1×6
11 9 6 2 -3 -9
Or with a recursive filter
C = filter(-1,[1 -1],A,B);
C = C(2:end)
C = 1×6
11 9 6 2 -3 -9
  1 Comment
Arif Hoq
Arif Hoq on 16 Sep 2022
Edited: Arif Hoq on 16 Sep 2022
thank you very much.
a=load("allmat.mat");
allmat=a.allmat;
C(1) = allmat(1,6) - allmat(1,5);
for i = 2:120
C(i) = allmat(i-1,6) - allmat(i,5);
end
C=C';
allmat(2:end,6)=C
allmat = 121×10
0 0 160.0000 80.0000 0 160.0000 80.0000 0 160.0000 80.0000 -1.3713 0 0 0 -0.4571 160.0000 0 0 0 0 -1.6463 0 0 0 -0.5488 160.4571 0 0 0 0 -0.9919 0 0 0 -0.3306 0.5488 0 0 0 0 -0.8804 0 0 0 -0.2935 0.3306 0 0 0 0 2.1362 0 0 0 0.7121 0.2935 0 0 0 0 5.4360 0 0 0 1.8120 -0.7121 0 0 0 0 2.1003 0 0 0 0.7001 -1.8120 0 0 0 0 -7.7674 0 0 0 -2.5891 -0.7001 0 0 0 0 -5.1723 0 0 0 -1.7241 2.5891 0 0 0 0
but the column 6 would be

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Arif Hoq
Arif Hoq on 16 Sep 2022
Edited: Arif Hoq on 16 Sep 2022
At last got the solution !!!!
a=load("allmat.mat");
allmat=a.allmat;
for i=1:size(allmat,1)
allmat(i,11)=allmat(i,6)-allmat(i,5);
allmat(i+1,6)=allmat(i,11);
allmat(i+1,11)=allmat(i+1,6)-allmat(i+1,5);
end
allmat(:,6)=allmat(:,11)
allmat = 122×11
0 0 160.0000 80.0000 0 160.0000 80.0000 0 160.0000 80.0000 160.0000 -1.3713 0 0 0 -0.4571 160.4571 0 0 0 0 160.4571 -1.6463 0 0 0 -0.5488 161.0059 0 0 0 0 161.0059 -0.9919 0 0 0 -0.3306 161.3365 0 0 0 0 161.3365 -0.8804 0 0 0 -0.2935 161.6300 0 0 0 0 161.6300 2.1362 0 0 0 0.7121 160.9179 0 0 0 0 160.9179 5.4360 0 0 0 1.8120 159.1059 0 0 0 0 159.1059 2.1003 0 0 0 0.7001 158.4058 0 0 0 0 158.4058 -7.7674 0 0 0 -2.5891 160.9949 0 0 0 0 160.9949 -5.1723 0 0 0 -1.7241 162.7190 0 0 0 0 162.7190
  1 Comment
Arif Hoq
Arif Hoq on 16 Sep 2022
nice. thank you so much. It's better to use vectorization rather than loop.

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