I am trying to find the column space of a matrix

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Taylor
Taylor 2023-7-13
评论： Carter Stahly 2024-11-7，19:05
Ran in:
I am working on a lab for my class and am having issues finding the column soace for the matrix.
A = [1,1,0,2,0;0,1,1,3,0;2,0,0,0,1;3,1,0,2,1;2,1,1,3,0;1,0,0,2,1]
A = 6×5
1 1 0 2 0 0 1 1 3 0 2 0 0 0 1 3 1 0 2 1 2 1 1 3 0 1 0 0 2 1
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This is the matrix that I am using. Tried the code
rrefA = rref(A)
rrefA = 6×5
1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0
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pivotColumns = rrefA(:,1:end-1)
pivotColumns = 6×4
1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0
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basisColumnSpace = A(:,pivotColumns)
Index in position 2 is invalid. Array indices must be positive integers or logical values.
but i cant get it to work I keep getting a error that i cant clear. I am wondering if there is another way to find the column space with the basic MatLab package. I would apperciate any help.
Thank You

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回答（1 个）

ProblemSolver
ProblemSolver 2023-7-13
@Taylor -- You just need to use this:
pivotColumns = find(any(rrefA, 1));
I hope this works!
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Walter Roberson
Walter Roberson 2024-11-7，18:52
I believe that @Torsten is providing a counter-example to illustrate the failure of @ProblemSolver approach. I do not believe that Torsten is attempting to illustrate a correct general method.
Carter Stahly
Carter Stahly 2024-11-7，19:05
That would make sense, thank you for the clarification.

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