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<div class="moz-cite-prefix">Le 07/02/2020 à 00:02, Samuel Gougeon a
écrit :<br>
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<blockquote type="cite"
cite="mid:37aed125-0a95-f061-ef67-7e8e7751c0a3@free.fr">
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<div class="moz-cite-prefix">Le 06/02/2020 à 10:41, Federico
Miyara a écrit :<br>
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cite="mid:a6eb0c6e-7917-a5d5-f106-448296f2a07e@fceia.unr.edu.ar">
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<font face="Courier New">Dear All,<br>
<br>
Just in case somebody is interested, find attached a Scilab
function to compute the sine integral function Si (the
integral from 0 to x of the sinc function), which cannot be
expressed in closed form with elementary functions.<br>
<br>
<i>It is preliminary, it doesn't test for appropriate input
argument.<br>
<br>
It works for real or complex matrices or N-D arrays.<br>
<br>
It can be easily modified to get the cosine integral
function.<br>
</i></font></blockquote>
<br>
<p>Great work, Federico! Just a comment: IMHO, so short functions
names should really be avoided.<br>
The shorter the name, the more probable are collisions with
other users common variables.<br>
<br>
By the way, i am wondering about a similar expint() function =
integral of dt*exp(t)/t.<br>
<br>
From there, the linearity of the integration operator and the
Euler formula would yield<br>
in a trivial way sinint(a) and cosint(a), with a (almost)
one-line definition using <br>
expint([-a a]*%i).<br>
</p>
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<p>Of course, the same expint could then be used as well for
integral(dt.sh(t)/t), <br>
integral(dt.ch(t)/t), etc. The exp familly is great, and, IMHO,
there would be<br>
no need to create N specific functionint for trivial expint
combinations.<br>
Just a good set of expint applications examples, in the expint
documentation.</p>
Samuel<br>
<br>
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