For Loop operating with last and first entry of array

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Manuel Fuelling
Manuel Fuelling 2018-4-4
评论： David Fletcher 2018-4-4
If i have an array like this:
A=[1;5;6;8];
and i apply a simple for loop like this:
for k=1:4
B(k)=A(k)+A(k+1);
end
How can i write the code, so the last entry of my array A makes the operation with the first entry aswell, namely 8+1=9?

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回答（1 个）

David Fletcher
David Fletcher 2018-4-4
编辑：David Fletcher 2018-4-4
Like this?
A=[1;5;6;8];
B=A(1:length(A))+[A(2:length(A));A(1)]
B =
6
11
14
9
  2 个评论
Manuel Fuelling
Manuel Fuelling 2018-4-4
My problem is different than the example i gave:
Coeff is a 4x4 Matrix
for m=1:3
syms x y z
eqns = [Coeff(m,1)*x+Coeff(m,2)*y+Coeff(m,3)*z+Coeff(m,4) == 0, Coeff(m+1,1)*x+Coeff(m+1,2)*y+Coeff(m+1,3)*z+Coeff(m+1,4) == 0];
vars = [x y z];
[solX, solY, solZ] = solve(eqns, vars);
arbpt_sym=[solX;solY;solZ];
arbpt_one_point=(double(arbpt_sym)); %mache sie als double
arbpt(:,m) = arbpt_one_point;
end
the last iteration should operate with the last row and first row of Coeff
David Fletcher
David Fletcher 2018-4-4
So you want it to operate as in the previous example but summing successive rows of a 2D matrix (and the last and first row) rather than the columns of the 1D matrix that you presented as your example?
Like this:
A=[1 1 1 1;2 2 2 2;3 3 3 3;4 4 4 4]
B=A(1:size(A),:)+[A(2:size(A),:);A(1,:)]
A =
1 1 1 1
2 2 2 2
3 3 3 3
4 4 4 4
B =
3 3 3 3
5 5 5 5
7 7 7 7
5 5 5 5

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