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<font face="Courier New">Stéphane,<br>
<br>
In the meantime, a workaround is to toggle simplification off:<br>
<br>
simp_mode(%f).<br>
<br>
This inhibits simplification.<br>
<br>
Regards,<br>
<br>
Federico Miyara<br>
<br>
</font><br>
<div class="moz-cite-prefix">On 20/03/2020 10:42, Stéphane Mottelet
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:80458f49-e6d8-e414-1618-8f1e99f2fe6a@utc.fr">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<p>(num,den) calling style seems to be OK:</p>
<p>--> [a,b]=simp(prod(q.num),prod(q.den))<br>
a = <br>
<br>
2 3 4<br>
3.432D-17 +1.230D-16s +3.079D-16s +5.709D-17s +3.432D-17s <br>
<br>
b = <br>
<br>
2 3 4<br>
1.0000004 +61.501079s +59.597296s +14.304769s +s <br>
</p>
<p>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 :<br>
</p>
<p>--> clean(a/b)<br>
ans =<br>
<br>
<br>
0 <br>
-- <br>
<br>
1 <br>
</p>
<p>which is OK to me when you see this:<br>
</p>
<p>--> w=10^(1:6); abs(horner(a/b,%i*w))<br>
ans =<br>
<br>
2.224D-17 3.415D-17 3.432D-17 3.432D-17 3.432D-17
3.432D-17<br>
</p>
<p>S.<br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">Le 20/03/2020 à 14:10, Stéphane
Mottelet a écrit :<br>
</div>
<blockquote type="cite"
cite="mid:575e8cc6-3691-a1b9-b641-76e9e12f6c76@utc.fr">
<meta http-equiv="Content-Type" content="text/html;
charset=UTF-8">
<p>Hello Frederico,</p>
<p>The problem is in simp() :</p>
<p>---> rlist(prod(a.num),prod(a.den),a.dt)<br>
ans =<br>
<br>
2
3 4 <br>
3.432D-17 + 1.230D-16s + 3.079D-16s + 5.709D-17s +
3.432D-17s <br>
--------------------------------------------------------------
<br>
2 3
4 <br>
1.0000004 + 61.501079s + 59.597296s + 14.304769s +
s <br>
<br>
<br>
---> simp(rlist(prod(a.num),prod(a.den),a.dt))<br>
ans =<br>
<br>
2
3 4 <br>
3.432D-17 + 1.230D-16s + 3.079D-16s + 5.709D-17s +
3.432D-17s <br>
--------------------------------------------------------------
<br>
<br>
1 <br>
</p>
<p>S.<br>
</p>
<div class="moz-cite-prefix">Le 17/03/2020 à 10:30, Federico
Miyara a écrit :<br>
</div>
<blockquote type="cite"
cite="mid:d2aadaf6-b35f-850b-797b-ad627bbf624f@fceia.unr.edu.ar">
<meta http-equiv="content-type" content="text/html;
charset=UTF-8">
<br>
<font face="Courier New">Dear all, <br>
<br>
Look at this code (the coefficients are actually the result
of pevious calculations):<br>
</font><span style="color:rgb(0,0,0);"><br>
</span><span style="color:rgb(0,0,0);">NUM</span> <span
style="color:rgb(92,92,92);">=</span> <span
style="color:rgb(74,85,219);">[</span><span
style="color:rgb(188,143,143);">5.858D-09</span> <span
style="color:rgb(92,92,92);">+</span> <span
style="color:rgb(188,143,143);">2.011D-08</span><span
style="color:rgb(92,92,92);">*</span><span
style="color:rgb(218,112,214);">%s</span> <span
style="color:rgb(92,92,92);">+</span> <span
style="color:rgb(188,143,143);">4.884D-08</span><span
style="color:rgb(92,92,92);">*</span><span
style="color:rgb(218,112,214);">%s</span><span
style="color:rgb(92,92,92);">^</span><span
style="color:rgb(188,143,143);">2</span> <span
style="color:rgb(255,170,0);">...</span> <br>
<span style="color:rgb(188,143,143);">5.858D-09</span>
<span style="color:rgb(92,92,92);">+</span> <span
style="color:rgb(188,143,143);">8.796D-10</span><span
style="color:rgb(92,92,92);">*</span><span
style="color:rgb(218,112,214);">%s</span> <span
style="color:rgb(92,92,92);">+</span> <span
style="color:rgb(188,143,143);">7.028D-10</span><span
style="color:rgb(92,92,92);">*</span><span
style="color:rgb(218,112,214);">%s</span><span
style="color:rgb(92,92,92);">^</span><span
style="color:rgb(188,143,143);">2</span><span
style="color:rgb(74,85,219);">]</span> <span
style="color:rgb(0,0,0);"><br>
DEN</span> <span style="color:rgb(92,92,92);">=</span> <span
style="color:rgb(74,85,219);">[</span><span
style="color:rgb(188,143,143);">0.1199597</span> <span
style="color:rgb(92,92,92);">+</span> <span
style="color:rgb(188,143,143);">7.2765093</span><span
style="color:rgb(92,92,92);">*</span><span
style="color:rgb(218,112,214);">%s</span> <span
style="color:rgb(92,92,92);">+</span> <span
style="color:rgb(218,112,214);">%s</span><span
style="color:rgb(92,92,92);">^</span><span
style="color:rgb(188,143,143);">2</span> <span
style="color:rgb(255,170,0);">...</span> <br>
<span style="color:rgb(188,143,143);"> 8.336136</span> <span
style="color:rgb(92,92,92);">+</span> <span
style="color:rgb(188,143,143);">7.0282601</span><span
style="color:rgb(92,92,92);">*</span><span
style="color:rgb(218,112,214);">%s</span> <span
style="color:rgb(92,92,92);">+</span> <span
style="color:rgb(218,112,214);">%s</span><span
style="color:rgb(92,92,92);">^</span><span
style="color:rgb(188,143,143);">2</span><span
style="color:rgb(74,85,219);">]</span> <span
style="color:rgb(0,0,0);"><br>
q = NUM</span><span style="color:rgb(92,92,92);">./</span><span
style="color:rgb(0,0,0);">DEN<br>
</span> <br>
Running it yields<br>
<br>
5.858D-09 +2.011D-08s +4.884D-08s² 5.858D-09 +8.796D-10s
+7.028D-10s² <br>
----------------------------------
---------------------------------- <br>
0.1199597 +7.2765093s +s² 8.336136
+7.0282601s +s² <br>
<br>
This is, correctly, a two-component rational vector with the
expected numerators and denominators. <br>
<br>
Now let's evaluate <br>
<br>
q = <span style="color:rgb(50,185,185);">prod</span><span
style="color:rgb(74,85,219);">(</span><span
style="color:rgb(0,0,0);">NUM</span><span
style="color:rgb(92,92,92);">./</span><span
style="color:rgb(0,0,0);">DEN</span><span
style="color:rgb(74,85,219);">)</span> <br>
<br>
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<br>
<br>
3.432D-17 +1.230D-16s +3.079D-16s² +5.709D-17s³
+3.432D-17s⁴ <br>
------------------------------------------------------------
<br>
1 <br>
<br>
The numeratoris right, but the expected denominator has been
just replaced by 1<br>
<br>
However, rewriting the command as<br>
<br>
<span style="color:rgb(50,185,185);">prod</span><span
style="color:rgb(74,85,219);">(</span><span
style="color:rgb(0,0,0);">NUM</span><span
style="color:rgb(74,85,219);">)</span><span
style="color:rgb(92,92,92);">/</span><span
style="color:rgb(50,185,185);">prod</span><span
style="color:rgb(74,85,219);">(</span><span
style="color:rgb(0,0,0);">DEN</span><span
style="color:rgb(74,85,219);">)<br>
<br>
</span>we get the expected result:<br>
<br>
3.432D-17 +1.230D-16s +3.079D-16s² +5.709D-17s³
+3.432D-17s⁴ <br>
------------------------------------------------------------
<br>
1.0000004 +61.501079s +59.597296s² +14.304769s³
+s⁴ <br>
<br>
This is quite strange!<br>
<br>
Now we repeat with simpler polynomials:<br>
<br>
NUM = [1-%s 2-%s]<br>
DEN = [1+%s 2+%s]<br>
q = NUM./DEN <br>
<br>
We get <br>
<br>
1 -s 2 -s <br>
---- ---- <br>
1 +s 2 +s <br>
<br>
Now evaluate<br>
<br>
prod(NUM./DEN)<br>
<br>
The result is the expected one!<br>
<br>
2 -3s +s² <br>
--------- <br>
2 +3s +s² <br>
<br>
The behavior seems to depend on the type of polynomials. <br>
<br>
Is this a bug or there is something I'm not interpreting
correctly?<br>
<br>
Regards,<br>
<br>
Federico Miyara<br>
<span style="color:rgb(74,85,219);"></span> <br>
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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
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<pre class="moz-signature" cols="72">--
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
<a class="moz-txt-link-freetext" href="http://www.utc.fr/~mottelet" moz-do-not-send="true">http://www.utc.fr/~mottelet</a>
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