Factoring
- To: mathgroup at smc.vnet.net
- Subject: [mg65069] Factoring
- From: "Matt" <anonmous69 at netscape.net>
- Date: Tue, 14 Mar 2006 05:59:48 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Hello Mathgroup, I'm sure that I've overlooked something obvious, but for the past two and a half hours, I've been trying to figure out how to use built-in Mathematica functions to just factor the imaginary number 'I' out of this: 4*I*r^2*Sin[2*θ] + I*r^5*Sin[5*θ] using Factor[] gives me I*r^2*(4*Sin[2*θ] + r^3*Sin[5*θ]) using FactorTerms[] gives me I*(4*r^2*Sin[2*θ] + r^5*Sin[5*θ]) which is what I want, but as soon as I add in a common numerical factor, it also factors that out as well, e.g. 4*I*r^2*Sin[2*θ] + 8*I*r^5*Sin[5*θ] I finally just decided to divide the whole thing by 'I', and do some reconstruction of my expression, but I have the distinct feeling I've totally missed something very simple. As an additional example, what if I just wanted to extract 2*x*I out of the following: 4*x*I*Sin[t] + 28*x^3*I*Cos[t] how would I do that? In general, I'm looking for a function that says "Given an expression 'expr' and another expression 'sub' that is common to all additive terms of 'expr', give a result that is the product of 'sub' and the result of factoring 'sub' out of 'expr'". Thanks, Matt
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