Help with jumping one position using circshift function in a for loop

조회 수: 2 (최근 30일)
Scott Banks
Scott Banks 2023년 8월 15일
댓글: Voss 2023년 8월 17일
Hi there,
I am trying to create a transformation matrix for the matrix stiffness method, and to save time I am using the circshift function in a for loop.
So, I am starting off with this
n = 12;
T = zeros(2,n);
T(1,1) = 1;
T(2,2) = 1
for i = 1:9
Tn(:,:,i) = circshift(T,[0,i])
end
However, every 3rd interation I want the values (the 1's) to shift one extra place to the right. So I want the Tn matrix to follow this pattern:
Tn = [1 1 0 1 1 0 1 1 0 1 1 0;
0 1 1 0 1 1 0 1 1 0 1 1]
I guessed at trying this:
for i = 1:9
Tn(:,:,i) = circshift(T,[0,i])
if i == 3,6,9
Tn(:,:,i) = circshift(T,[0,i+1])
endif
end
But it didn't work.
I hope I have explained this clearly. Can somebody help please?
Many thanks.
  댓글 수: 1
Chhayank Srivastava
Chhayank Srivastava 2023년 8월 15일
Could you clarify what do you mean when you say you want Tn to follow that pattern, does that mean after running the loop Tn should look like that?

댓글을 달려면 로그인하십시오.

이 질문에 답변하려면 로그인하십시오.

채택된 답변

Star Strider
Star Strider 2023년 8월 15일
Ran in:
The circshift function does not duplicate any values, so I don’t understand how you expect to get the ‘Tn’ matrix at the end.
I’m not certain what result you want otherwise.
Try this —
n = 12;
T = zeros(2,n);
T(1,1) = 1;
T(2,2) = 1
T = 2×12
1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0
si = 0;
for i = 1:9
sia = rem(i,3) == 0;
si = [si+1+sia] % Shift Increments
Tn(:,:,i) = circshift(T,[0,si]);
end
si = 1
si = 2
si = 4
si = 5
si = 6
si = 8
si = 9
si = 10
si = 12
Tn
Tn =
Tn(:,:,1) = 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 Tn(:,:,2) = 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 Tn(:,:,3) = 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 Tn(:,:,4) = 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 Tn(:,:,5) = 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 Tn(:,:,6) = 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 Tn(:,:,7) = 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 Tn(:,:,8) = 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 Tn(:,:,9) = 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0
Ths ‘si’ values are the increments provided to circshift so that you can keep track of them. (Suppress that line’s output when its display is no longer necessary.)
.

추가 답변 (3개)

Voss
Voss 2023년 8월 15일
편집: Voss 2023년 8월 17일
Ran in:
n = 12;
T = zeros(2,n);
T(1,1) = 1;
T(2,2) = 1
T = 2×12
1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0
Here's one way to generate that Tn from this T using circshift in a loop:
Tn = zeros(2,n,8);
shift = 0;
for i = 1:size(Tn,3)
if mod(i,2) == 1
shift = shift+1;
end
Tn(:,:,i) = circshift(T,[0,shift-1]);
shift = shift+1;
end
disp(Tn);
(:,:,1) = 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 (:,:,2) = 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 (:,:,3) = 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 (:,:,4) = 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 (:,:,5) = 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 (:,:,6) = 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 (:,:,7) = 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 (:,:,8) = 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1
Chhayank Srivastava
Chhayank Srivastava 2023년 8월 15일
Ran in:
Hi,
I see some issue with the if statement mentioned above.
So just fixing the if statement
n = 12;
T = zeros(2,n);
T(1,1) = 1;
T(2,2) = 1;
for i = 1:9
Tn(:,:,i) = circshift(T,[0,i]);
if mod(i,3) == 0
Tn(:,:,i) = circshift(T,[0,i+1]);
end
end
Tn
Tn =
Tn(:,:,1) = 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 Tn(:,:,2) = 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 Tn(:,:,3) = 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 Tn(:,:,4) = 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 Tn(:,:,5) = 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 Tn(:,:,6) = 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 Tn(:,:,7) = 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 Tn(:,:,8) = 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 Tn(:,:,9) = 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1
Moreover, I am assuming after running the program you want the Tn to look like
Tn = [1 1 0 1 1 0 1 1 0 1 1 0;
0 1 1 0 1 1 0 1 1 0 1 1];
But in the above code you are generating a 3D matrix.
A simpler solution would be just to use repmat and transformation matrix
T = [1,1,0;0,1,1];
Tn = repmat(T,1,4)
Tn = 2×12
1 1 0 1 1 0 1 1 0 1 1 0 0 1 1 0 1 1 0 1 1 0 1 1
But, going by your method
clear;clc;
n = 12;
T = zeros(2,n);
T(1,1) = 1;
T(2,2) = 1;
for i = 1:9
if mod(i,2) == 0
T = circshift(T,[0,2]);
Tn(:,:,i) = T;
else
T = circshift(T,[0,1]);
Tn(:,:,i) = T;
end
end
Tn = Tn(:,:,1)+Tn(:,:,2)+Tn(:,:,3)+Tn(:,:,4)+Tn(:,:,5)+Tn(:,:,6)+Tn(:,:,7)+Tn(:,:,8)
Tn = 2×12
1 1 0 1 1 0 1 1 0 1 1 0 0 1 1 0 1 1 0 1 1 0 1 1
Scott Banks
Scott Banks 2023년 8월 15일
Hi guys,
thank you for your repsonses.
Sorry for the confusion for the final Tn matrix. It was a poor way of getting across my idea.
Really, it should look like how Star Strider answered. Which was 9 different matrices in the form of:
Tn =
Tn(:,:,1) =
0 1 0 0 0 0 0 0 0 0 0 0
0 0 1 0 0 0 0 0 0 0 0 0
Tn(:,:,2) =
0 0 1 0 0 0 0 0 0 0 0 0
0 0 0 1 0 0 0 0 0 0 0 0
Tn(:,:,3) =
0 0 0 0 1 0 0 0 0 0 0 0
0 0 0 0 0 1 0 0 0 0 0 0
Tn(:,:,4) =
0 0 0 0 1 0 0 0 0 0 0 0
0 0 0 0 0 1 0 0 0 0 0 0
Tn(:,:,5) =
0 0 0 0 0 1 0 0 0 0 0 0
0 0 0 0 0 0 1 0 0 0 0 0
Tn(:,:,6) =
0 0 0 0 0 0 0 1 0 0 0 0
0 0 0 0 0 0 0 0 1 0 0 0
Tn(:,:,7) =
0 0 0 0 0 0 0 1 0 0 0 0
0 0 0 0 0 0 0 0 1 0 0 0
Tn(:,:,8) =
0 0 0 0 0 0 0 0 1 0 0 0
0 0 0 0 0 0 0 0 0 1 0 0
Tn(:,:,9) =
0 0 0 0 0 0 0 0 0 0 1 0
0 0 0 0 0 0 0 0 0 0 0 1
  댓글 수: 5
이전 댓글 3개 표시
Star Strider
Star Strider 2023년 8월 17일
@Scott Banks — Thank you!
If I provided the correct result, please Accept my Answer.
(Comment also posted earlier)
Voss
Voss 2023년 8월 17일
@Scott Banks: I'm a little confused because if Tn(:,:,3) and T(n:,:,4) are both shifted to the right, then they are still the same as each other, which contradicts your statement that they should not be the same as each other.
Can you just write down the complete 3D array as it should be?

댓글을 달려면 로그인하십시오.

카테고리

Help Center 및 File Exchange에서 Programming에 대해 자세히 알아보기

태그

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by