Minreal function difference between 2021a and 2021b
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Roberto Echeverria
on 16 Feb 2022
Commented: Roberto Echeverria
on 22 Feb 2022
Hello all,
i am trying to simplifiy the following transfer function
num= [0 2.326783565332 0.047642481534536 1.1320523206336 0.018636773326054 0.1736525620563 0.0018797084587909 0.0095824683611615 5.0490779499017e-05 0.0001278775430483 3.1601961291737e-07 -4.7792321851035e-08 4.7241839384478e-12 1.6520593468991e-16 -3.5261492799393e-35]
den=[1 0.16677519120767 0.49411474213873 0.072903194148789 0.077462329441744 0.0095429580373996 0.0043848511975007 0.00044880580115597 6.2185817443617e-05 5.5616071215642e-06 3.4904054871597e-08 -1.8966547971896e-09 -1.5452863299211e-11 -2.9766685962549e-15 4.4489378695401e-21]
In matlab 2021a with a tolerance of 0.005 i get:
num=[0 2.326783565332 0.0242847369269 0.29192839103876 -6.2309086400998e-20]
den = [1 0.15310693671003 0.13130203172257 0.012309590052138 9.2125282212156e-05]
While in matlab 2021b with the same tolerance i get:
num=[0 2.326783565332 0.041644199007858 1.1327911885271 0.015731663720654 0.17402398971009 0.0014368084118137 0.0096420548390914 2.6156798199821e-05 0.00013131681404352 -1.2992874796127e-08 -4.5425159381868e-13 9.6955289981649e-32]
den=[1 0.16403829533202 0.49402991560459 0.071610816843538 0.077446228810322 0.0093570713626183 0.0043874423008049 0.00044020501132602 6.2578618017865e-05 5.5506274585318e-06 4.249926757687e-08 8.1746675586304e-12 -1.2218020065151e-17]
There is quite a difference in order, but which one is the correct one? There is not any notice about changes in this function in the 2021b list of changes, or at least, i could not find anything.
Kind regards
Roberto
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Accepted Answer
Paul
on 17 Feb 2022
Running 2021b in the Answers facility yieds results that are very close to, but not exactlyl the same as, what you got in 2021a.
num= [0 2.326783565332 0.047642481534536 1.1320523206336 0.018636773326054 0.1736525620563 0.0018797084587909 0.0095824683611615 5.0490779499017e-05 0.0001278775430483 3.1601961291737e-07 -4.7792321851035e-08 4.7241839384478e-12 1.6520593468991e-16 -3.5261492799393e-35];
den= [1 0.16677519120767 0.49411474213873 0.072903194148789 0.077462329441744 0.0095429580373996 0.0043848511975007 0.00044880580115597 6.2185817443617e-05 5.5616071215642e-06 3.4904054871597e-08 -1.8966547971896e-09 -1.5452863299211e-11 -2.9766685962549e-15 4.4489378695401e-21];
format long e
[numr,denr] = minreal(num,den,0.005) % obsolete usage?
I get these exact same results on my local installation (2021b, Update 2). Can you post the exact code you ran in 2021b?
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