Convolve: Different Looking Results. (2)
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- Subject: [mg130623] Convolve: Different Looking Results. (2)
- From: Polar Coords <pcoords29 at gmail.com>
- Date: Fri, 26 Apr 2013 23:08:37 -0400 (EDT)
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Sorry about my last incomplete mail.
Consider the following in Mathematica 8 ( It's a convolution as in Laplace
In:= Convolve[Exp[-x] UnitStep[x], Sin[2 x] UnitStep[x], x, y,
Assumptions -> y > 0]
Out= -(2/5) (Cos[2 y] - Cosh[y] - Cos[y] Sin[y] + Sinh[y])
Now , use t instead of y
In:= Convolve[Exp[-x] UnitStep[x], Sin[2 x] UnitStep[x], x, t,
Assumptions -> t > 0]
Out= 1/5 (2 E^-t - 2 Cos[2 t] + Sin[2 t])
They're equivalent, but why the different looking results? We have the
Out results if we use symbols a to w, but as in Out if using y
or z !
Do members have the same results in Mathematica 9?
Finally, on a lighter note, one usually convolves 2 functions of x to get a third function of x. I can't suss out why Mathematica gives the answer in terms of
a new variable.
So, if I want to convolve 2 output functions of t, then I need to change to
another variable and tell it to give the answer in terms of t. A hassle.
Thanks for your help.
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