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isequal polynomials, why matlab cannot show matrix polynomials are equal?

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Jesper Ankersen 2020-12-25

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评论： Walter Roberson 2020-12-25

Merry Christmas to all matlab folks. I have a question, can anyone tell me why i get the following result, even though the to matrix polynomials are equal ?

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Walter Roberson 2020-12-25

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在 MATLAB Online 中打开

What shows up for

H - HH

Jesper Ankersen 2020-12-25

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Thats a good work around the issue. Doing this results in zero.

Thanks

Image Analyst 2020-12-25

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What is the value of s? Can you give us code? We can run code but cannot run a screenshot.

Walter Roberson 2020-12-25

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is it possible that those were matrices of transfer functions? If so perhaps some details were different such as input delays. A mat file would have helped.

Jesper Ankersen 2020-12-25

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I will gladly send code, but the first answer from Walter was very helpfull, since i only needed to ensure that the two matrices were equal.

I think the main problem was that one matrix (H) had a term like: 2(s+2)

and the other (HH) would have an equivalent term like: 2s+4

so isequal were not able to sort these, but when subtracting H - HH the issue was no longer.

Btw kudos to u two guys for answering so many matlab questions, ive seen youre names often when looking at matlab answers! :)

Walter Roberson 2020-12-25

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在 MATLAB Online 中打开

Ah, yes, isequal of symbolic checks for whether they are expressed the same way.

isAlways(H == HH)

Jesper Ankersen 2020-12-25

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Okay, I see. So "isalways" will check for all possible ways the symbolic expression can be formulated.

I am curious, are u (walter), a matlab enthusiast or hired by matlab ?

Walter Roberson 2020-12-25

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