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Re: Solving complex equations

  • To: mathgroup at smc.vnet.net
  • Subject: [mg91204] Re: [mg91157] Solving complex equations
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Sat, 9 Aug 2008 07:46:33 -0400 (EDT)
  • Organization: Mathematics & Statistics, Univ. of Mass./Amherst
  • References: <200808081112.HAA11483@smc.vnet.net>
  • Reply-to: murray at math.umass.edu

In such situations, ComplexExpand is your friend: it tells Mathematica 
to treat symbolic variables as real, which I presume is your intent here.

So here's a start.  Obviously the process could be encapsulated into a 
function.  I've used the infix @ notation for simplicity.

   eq = a+b I+c+d I==3+4 I;

   {ComplexExpand@Re@First@eq==ComplexExpand@Re@Last@eq,
    ComplexExpand@Im@First@eq==ComplexExpand@Im@Last@eq}
{a+c==3,b+d==4}

Adel Elsabbagh wrote:
> Dear all,
> 
> If I have a complex equation in the form of
> a+b I + c+d I == 3+ 4 I
> where a, b, c, and d are all assumed to be real.
> 
> How do I tell Mathematica 6 to separate the real and imaginary parts to make
> two equations in the form of
> a + c == 3, and
> b + d == 4.
> 
> I need this to apply it on a long list of equations.
> 
> Thanks in advance!
> 

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305


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