I've got a complicated expression, which looks like: e(4ik+3iω+ip)−e(4ik+2iω+2ip)−e(4ik+2iω)+e(4ik+iω+ip)+2e(2ik+4iω+ip)−e(2ik+3iω+2ip)−e(2ik+3iω) + ...
How would you do to factor the exponentials with the same power of k, i.e. e(4ik)(...) + e(2ik)(...) and so on?
Using both ideas we can formulate a complete answer (assume that expr(k) is the expression in terms of phases in powers of k that we want to factor):
f1(k) = expr(-I*log(k)); f1
g1(k) = f1.canonicalize_radical(); g1
g1(k).coefficient(k,4)
Maybe by a change of variables:
sage: var('k,w,p')
sage: expr(k,w,p)=exp(4ik+3iw+ip)-exp(4ik+2iw+2ip)-exp(4ik+2iw)+exp(4ik+iw+ip)+2exp(2ik+4iw+ip)-
exp(2ik+3iw+2ip)-exp(2ik+3i*w)
sage: f(k,w,p)=expr(log(k),log(w),log(p))
sage: g(k,w,p)=f.canonicalize_radical()
sage: g(exp(k),exp(w),exp(p)).factor()
I would probably try using the factor method.
sage: var('x,y,z')
(x, y, z)
sage: expr=exp(4*x-2*y+4*z)+exp(4*x-3*y+5*z)
sage: expr.factor()
(e^y + e^z)*e^(4*x - 3*y + 4*z)
Perhaps the manual will contain useful info on that as well.
Thanks, but you can see this doesn't do the job: the goal was to collect the terms in exp(4x), and so on (try adding for instance exp(2x-3y+5z) and factoring, it does something correct but is not what I need). I thought it'd be useful a previous step transforming the exp(2x) into z and exp(4x) into z^2, etc and then factoring, but I am not able to get the substitution done..
Asked: 2015-10-08 10:34:33 +0100
Seen: 700 times
Last updated: Oct 11 '15
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