Le 07/02/2020 à 00:02, Samuel Gougeon a écrit :
Le 06/02/2020 à 10:41, Federico Miyara a écrit :
Dear All,
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.
/It is preliminary, it doesn't test for appropriate input argument.
It works for real or complex matrices or N-D arrays.
It can be easily modified to get the cosine integral function.
/
Great work, Federico! Just a comment: IMHO, so short functions names
should really be avoided.
The shorter the name, the more probable are collisions with other
users common variables.
By the way, i am wondering about a similar expint() function =
integral of dt*exp(t)/t.
From there, the linearity of the integration operator and the Euler
formula would yield
in a trivial way sinint(a) and cosint(a), with a (almost) one-line
definition using
expint([-a a]*%i).
Of course, the same expint could then be used as well for
integral(dt.sh(t)/t),
integral(dt.ch(t)/t), etc. The exp familly is great, and, IMHO, there
would be
no need to create N specific functionint for trivial expint combinations.
Just a good set of expint applications examples, in the expint
documentation.
Samuel
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