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<div class="moz-cite-prefix">Le 17/09/2019 à 15:19, Federico Miyara
a écrit :<br>
</div>
<blockquote type="cite"
cite="mid:cfa5b14b-2c38-e311-4e65-31b8ce9ad2f9@fceia.unr.edu.ar">
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<br>
<font face="Courier New">Stéphane,<br>
<br>
</font>
<blockquote type="cite"
cite="mid:f5461ea0-5168-5376-7bbb-f80c2798a663@utc.fr">
<p>--> x=1:0.1:2<br>
x =<br>
<br>
1. 1.1 1.2 1.3 1.4 1.5 1.6 1.7000000 1.8
1.9 2.</p>
</blockquote>
<br>
</blockquote>
nothing triggers it in actual Scilab version. This was just an
example of what could be displayed after the patch I propose (in its
last week version). But the discussion has been fruitfull and I will
propose something that will satisfy (I hope so) everyone.
<p>S.<br>
</p>
<p><br>
</p>
<blockquote type="cite"
cite="mid:cfa5b14b-2c38-e311-4e65-31b8ce9ad2f9@fceia.unr.edu.ar">
However I get this:<br>
<br>
> x=1:0.1:2<br>
x = <br>
<br>
1. 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.<br>
<br>
But it is true that x(7) - 1.7 yields 2.220D-16. Here there are
two problems, an arithmetic one and a display one. Formatting to a
sufficiently large number of digits the arithmetic problem (or
limitation, probably unsurmountable, originated in the
incompatibility of binary and decimal systems) is evident:<br>
<br>
> format(20)<br>
<br>
> x=1:0.1:2<br>
x = <br>
<br>
column 1 to 6<br>
<br>
1. 1.10000000000000009 1.19999999999999996
1.30000000000000004 1.39999999999999991 1.5<br>
<br>
column 7 to 11<br>
<br>
1.60000000000000009 1.70000000000000018 1.8
1.89999999999999991 2.<br>
<br>
<br>
Why this triggers showing several zeros I don't understand,
probably a bug, but it can be seen that it happens when the
numeric error affects te 16th decimal digit.<br>
<br>
</blockquote>
<br>
<blockquote type="cite"
cite="mid:cfa5b14b-2c38-e311-4e65-31b8ce9ad2f9@fceia.unr.edu.ar">
Regards,<br>
<br>
Federico Miyara<br>
<br>
<br>
<br>
<br>
<br>
<br>
<blockquote type="cite"
cite="mid:f5461ea0-5168-5376-7bbb-f80c2798a663@utc.fr"> -->
x(7) <br>
ans =<br>
<p> 1.6</p>
<p>--> x(7)-1.6 <br>
ans =<br>
<br>
0.<br>
<br>
--> x(8) </p>
<p> ans =<br>
<br>
1.7000000</p>
<p>--> x(8)-1.7 <br>
ans =<br>
<br>
2.220D-16</p>
<p>I think that we do agree about the fact that the actual
Scilab display<br>
</p>
<p>--> x=1:0.1:2<br>
x =<br>
<br>
1. 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9
2.</p>
<p>--> x(7) <br>
ans =<br>
</p>
<p> 1.6</p>
<p>--> x(7)-1.6 <br>
ans =<br>
<br>
0.<br>
<br>
--> x(8) <br>
ans =<br>
<br>
1.7</p>
<p>--> x(8)-1.7 <br>
ans =<br>
<br>
2.220D-16</p>
<p>is pretty but not correct/homogeneous/honest. The display
that is obtained with the patch (first lines of this email) is
correct+honest but not homogeneous. A pretty + mathematically
correct display would be:</p>
<p> </p>
<p>--> x=1:0.1:2<br>
x =<br>
<br>
1.0000000 1.1000000 1.2000000 1.3000000 1.4000000
1.0000005 1.6000000 1.7000000 1.8000000 1.9000000
2.0000000</p>
<p>--> x(7) <br>
ans =<br>
<br>
1.6</p>
<p>--> x(8) <br>
ans =<br>
<br>
1.7000000</p>
--> x(8)-1.7 <br>
<p> ans =<br>
<br>
2.220D-16</p>
<p>i.e. when the matrix to display is not a scalar, add always
trailing zeros for homogeneity, BUT when it is a scalar, add
trailing zeros only when the actual stored value is different
from the displayed value. <br>
</p>
<p>The first thing that you can see is that the default
format(10) would be very verbose, but this is tunable. A value
of 7 would be ok, but quite low for format("e"). <br>
</p>
<p>S.<br>
</p>
<div class="moz-cite-prefix">Le 13/09/2019 à 13:37, Stéphane
Mottelet a écrit :<br>
</div>
<blockquote type="cite"
cite="mid:32f0b55a-963d-ea1c-9256-705d669d3c4e@utc.fr">
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<div class="moz-cite-prefix">Le 13/09/2019 à 13:07, Samuel
Gougeon a écrit :<br>
</div>
<blockquote type="cite"
cite="mid:316628fe-a1ac-f129-0b7d-dddf68028273@free.fr">
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charset=UTF-8">
<div class="moz-cite-prefix">Le 12/09/2019 à 18:55, Stéphane
Mottelet a écrit :<br>
</div>
<blockquote type="cite"
cite="mid:5ca07ea9-bf8d-dd92-958c-6abac0ce5e1a@utc.fr">I
prefer the display after applying <a
class="moz-txt-link-freetext"
href="https://antispam.utc.fr/proxy/2/c3RlcGhhbmUubW90dGVsZXRAdXRjLmZy/antispam.utc.fr/proxy/2/c3RlcGhhbmUubW90dGVsZXRAdXRjLmZy/antispam.utc.fr/proxy/2/c3RlcGhhbmUubW90dGVsZXRAdXRjLmZy/codereview.scilab.org/#/c/20981/"
moz-do-not-send="true">https://codereview.scilab.org/#/c/20981/</a>:
<br>
<br>
--> x0=%pi/4;h=%eps/2 <br>
h = <br>
<br>
1.110D-16 <br>
<br>
--> cos(x0+%i*h) <br>
ans = <br>
<br>
0.7071068 - 7.850D-17i <br>
<br>
However, we could discuss if the arbitrary switch to "e"
mode is desirable or not, but since Scilab 6.0 we have got
used to this display mixing "v" and "e" mode... <br>
</blockquote>
<p><br>
</p>
<p>... and IMO it's very suitable. The only rule should be
that, <b><i>for a given format's width</i></b>, <b><i>the
more the number of significant displayed figures the
better.</i></b> When the exponent format is used, it
takes 4 or 5 digits (D+12, D+123). As a consequence, in v
mode, small (absolute) values should be displayed in
normal mode down to 4 non-significant 0 (e.g. 0.000012),
and switched to "e" mode beyond.</p>
<p>In v mode, forcing the display of 0.0123456 in "e" mode
on the (bad) reason that some other huge or tiny numbers
in the matrix are displayed in this mode, would print
1.234D-02, and so make invisible 2 significant figures.<br>
I do not see any reason that would impose the display mode
to be homogeneous over all elements of a matrix, possibly
canceling the display of significant figures in the given
format's width.</p>
</blockquote>
I agree Samuel. <br>
<blockquote type="cite"
cite="mid:316628fe-a1ac-f129-0b7d-dddf68028273@free.fr">
<p>Regards</p>
<p>Samuel</p>
<p><br>
</p>
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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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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="https://antispam.utc.fr/proxy/1/c3RlcGhhbmUubW90dGVsZXRAdXRjLmZy/www.utc.fr/~mottelet" moz-do-not-send="true">http://www.utc.fr/~mottelet</a>
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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
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