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Fractional Calculus & Inverse Laplace Transforms
*To*: mathgroup at smc.vnet.net
*Subject*: [mg35138] Fractional Calculus & Inverse Laplace Transforms
*From*: jonathan.landy at roche.com (Jonathan)
*Date*: Tue, 25 Jun 2002 19:55:23 -0400 (EDT)
*Sender*: owner-wri-mathgroup at wolfram.com
Hi,
I've been working on an inverse Laplace transform, here it is:
(1)
w 1
L-1 [ --------- * ----- ] , -1<a<1, a!=0
S^2 + w^2 s^a
I solved this by extending the following identity to fractional
powers of a:
L^-1 [ f(s)/s^a ] = (I^a o f)(t) = a indefinite integrals of f(t);
Now,for my solution I got an infinite series, this is alright
because the other method of solving the problem gave some
hypergeometric solutions that were more complicated.
I plugged my solution into mathematica and took the Laplace
trasform and it gave (1)! However if one gives a value for a, I get
a hypergeometric equation again. So my questions are: is mathematica
assuming that a is an integer the first time I ran the thing? Also
does anyone know if I can even make the assumption that I
did (that the identity for the inverse laplace works for fractional
a)? It appears that I can, because I tested it on some cases one can
do by hand, but that is by no means a proof that it works in general.
However, most of the stuff in fractional calculus is just a definition
anyways, so maybe this is ok? I don't know. Thanks for the help.
Also, please can you respond through the message board, because my
email account is not working very well right now.
thanks again.
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