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[MUG] Breaking Down Complex Expressions
| [MUG] Breaking Down Complex Expressions |
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Author: Torpey, Peter
Posted: Fri, 13 Sep 2002 08:44:11 -0400
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>> From: "Torpey, Peter" "PTorpey"
When expressions are long, complex, and contain many sub-expressions, it can
be difficult to take in the form of the expression and/or pick out the
important terms.
I'm wondering if there is a routine I missed in Maple, or simple procedures
for breaking down such expressions into sub-expressions.
As an example, I have:
> sol[3];
f[3](t) =
-1/2*exp(-1/2*(md*freq*cd+3*ks+2*kh-(md^2*freq^2*cd^2-2*md*freq*cd*ks+5*ks^2
)^(1/2))/cs*t)*p*(2*(md^2*freq^2*cd^2-2*md*freq*cd*ks+5*ks^2)^(1/2)*ks+(md^2
*freq^2*cd^2-2*md*freq*cd*ks+5*ks^2)^(1/2)*kh+ks*kh+4*ks^2-2*md*freq*cd*ks-m
d*freq*cd*kh)/(md^2*freq^2*cd^2-2*md*freq*cd*ks+5*ks^2)^(1/2)/(2*md*freq*cd*
ks+ks^2+md*freq*cd*kh+3*ks*kh+kh^2)+1/2*exp(-1/2*(md*freq*cd+3*ks+2*kh+(md^2
*freq^2*cd^2-2*md*freq*cd*ks+5*ks^2)^(1/2))/cs*t)*(4*ks^2+ks*kh-2*(md^2*freq
^2*cd^2-2*md*freq*cd*ks+5*ks^2)^(1/2)*ks-2*md*freq*cd*ks-md*freq*cd*kh-(md^2
*freq^2*cd^2-2*md*freq*cd*ks+5*ks^2)^(1/2)*kh)*p/(md^2*freq^2*cd^2-2*md*freq
*cd*ks+5*ks^2)^(1/2)/(2*md*freq*cd*ks+ks^2+md*freq*cd*kh+3*ks*kh+kh^2)+p*(2*
ks+kh)/(kh^2+(md*freq*cd+3*ks)*kh+ks*(2*md*freq*cd+ks))
Here, f[3](t) is expressed as a ong sequence of exponentials and factors.
What would be nice, if there were a method to put this in the form:
a*exp(c1*t)+b*exp(c2*t)+...
where the a, b, c1, c2, etc. have the appropriate values but are not written
out explicityly.
I remember using Macsyma (about 20 years ago!), and I think there was a
routine called "pickapart" or something like that. The routine would break
the expression down automatically into sub-expressions, i.e.,
f[3](t) = a*exp(c1*t)+b*exp(c2*t)+...
where,
a= ...
b= ...
c1= ...
c2=...
etc.
Does maple have such a utility? If not, is there another simple way?
Thanks for any help.
-- Pete
e-mail: "ptorpey"
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