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

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 ?

[Walter Roberson]

What shows up for

 H - HH

[Jesper Ankersen]

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

Thanks

[Image Analyst]

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

[Walter Roberson]

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]

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]

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

isAlways(H == HH)

[Jesper Ankersen]

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]

I have never worked for Mathworks; I am a volunteer.