(num,den) calling style seems to be OK:
--> [a,b]=simp(prod(q.num),prod(q.den))
a =
2 3 4
3.432D-17 +1.230D-16s +3.079D-16s +5.709D-17s +3.432D-17s
b =
2 3 4
1.0000004 +61.501079s +59.597296s +14.304769s +s
The problem is in %r_simp code, which does a cleaning, but not a
complete one. If fact we should have the same result when the cleaning
is done afterwards :
--> clean(a/b)
ans =
0
--
1
which is OK to me when you see this:
--> w=10^(1:6); abs(horner(a/b,%i*w))
ans =
2.224D-17 3.415D-17 3.432D-17 3.432D-17 3.432D-17 3.432D-17
S.
Le 20/03/2020 à 14:10, Stéphane Mottelet a écrit :
Hello Frederico,
The problem is in simp() :
---> rlist(prod(a.num),prod(a.den),a.dt)
ans =
2 3 4
3.432D-17 + 1.230D-16s + 3.079D-16s + 5.709D-17s + 3.432D-17s
--------------------------------------------------------------
2 3 4
1.0000004 + 61.501079s + 59.597296s + 14.304769s + s
---> simp(rlist(prod(a.num),prod(a.den),a.dt))
ans =
2 3 4
3.432D-17 + 1.230D-16s + 3.079D-16s + 5.709D-17s + 3.432D-17s
--------------------------------------------------------------
1
S.
Le 17/03/2020 à 10:30, Federico Miyara a écrit :
Dear all,
Look at this code (the coefficients are actually the result of
pevious calculations):
NUM = [5.858D-09 + 2.011D-08*%s + 4.884D-08*%s^2 ...
5.858D-09 + 8.796D-10*%s + 7.028D-10*%s^2]
DEN = [0.1199597 + 7.2765093*%s + %s^2 ...
8.336136 + 7.0282601*%s + %s^2]
q = NUM./DEN
Running it yields
5.858D-09 +2.011D-08s +4.884D-08s² 5.858D-09 +8.796D-10s
+7.028D-10s²
---------------------------------- ----------------------------------
0.1199597 +7.2765093s +s² 8.336136 +7.0282601s +s²
This is, correctly, a two-component rational vector with the expected
numerators and denominators.
Now let's evaluate
q = prod(NUM./DEN)
The prod documantation sys that the argument may be "an array of
reals, complex, booleans, polynomials or rational fractions". It
should provide the rational obtained by multiplying the twonumrators
and the two denominators. However, we get
3.432D-17 +1.230D-16s +3.079D-16s² +5.709D-17s³ +3.432D-17s⁴
------------------------------------------------------------
1
The numeratoris right, but the expected denominator has been just
replaced by 1
However, rewriting the command as
prod(NUM)/prod(DEN)
we get the expected result:
3.432D-17 +1.230D-16s +3.079D-16s² +5.709D-17s³ +3.432D-17s⁴
------------------------------------------------------------
1.0000004 +61.501079s +59.597296s² +14.304769s³ +s⁴
This is quite strange!
Now we repeat with simpler polynomials:
NUM = [1-%s 2-%s]
DEN = [1+%s 2+%s]
q = NUM./DEN
We get
1 -s 2 -s
---- ----
1 +s 2 +s
Now evaluate
prod(NUM./DEN)
The result is the expected one!
2 -3s +s²
---------
2 +3s +s²
The behavior seems to depend on the type of polynomials.
Is this a bug or there is something I'm not interpreting correctly?
Regards,
Federico Miyara
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--
Stéphane Mottelet
Ingénieur de recherche
EA 4297 Transformations Intégrées de la Matière Renouvelable
Département Génie des Procédés Industriels
Sorbonne Universités - Université de Technologie de Compiègne
CS 60319, 60203 Compiègne cedex
Tel : +33(0)344234688
http://www.utc.fr/~mottelet
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https://antispam.utc.fr/proxy/1/c3RlcGhhbmUubW90dGVsZXRAdXRjLmZy/lists.scilab.org/mailman/listinfo/users
--
Stéphane Mottelet
Ingénieur de recherche
EA 4297 Transformations Intégrées de la Matière Renouvelable
Département Génie des Procédés Industriels
Sorbonne Universités - Université de Technologie de Compiègne
CS 60319, 60203 Compiègne cedex
Tel : +33(0)344234688
http://www.utc.fr/~mottelet
_______________________________________________
users mailing list
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http://lists.scilab.org/mailman/listinfo/users
