Re: Finding the real part of a symbolic complex expression
- To: mathgroup at smc.vnet.net
- Subject: [mg126586] Re: Finding the real part of a symbolic complex expression
- From: Bob Hanlon <hanlonr357 at gmail.com>
- Date: Mon, 21 May 2012 05:57:55 -0400 (EDT)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
- References: <201205200635.CAA04268@smc.vnet.net>
expr = (a + I b) (c + I d);
Simplify[Re[expr] // ExpandAll, Element[{a, b, c, d}, Reals]]
a c - b d
Re[expr] // ComplexExpand
a c - b d
Bob Hanlon
On Sun, May 20, 2012 at 2:35 AM, Jacare Omoplata
<walkeystalkey at gmail.com> wrote:
> I wanted to find the real part of (a + I b)(c + I d) , assuming a,b,c and d are real, "I" being Sqrt[-1].
>
> So I tried,
>
> Re[(a + I b) (c + I d)] /. Assuming -> Element[{a, b, c, d}, Reals]
>
> Nothing happens. What I get for output is,
>
> Re[(a+I b) (c+I d)]
>
> I found out that I can use the function "ComplexExpand" to expand the expression assuming a,b,c and d to be real. But I'm curious to know if there a way to make Mathematica use "Re" to find the real part?
>
- References:
- Finding the real part of a symbolic complex expression
- From: Jacare Omoplata <walkeystalkey@gmail.com>
- Finding the real part of a symbolic complex expression