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Re: Real and Imaginary Parts of complex functions
Posted:
Feb 27, 2013 3:04 AM


Did you try a search in the Documentation Center? If you do, one of the things you'll find near the top of the hits is
Complex Numbers (Mathematica Guide)
which includes a list of functions. One of these is:
ComplexExpand  expand symbolic expressions into real and imaginary parts
Then look at the reference page for that; it's what you want here.
ComplexExpand[Re[1/(x + y I)]] x/(x^2 + y^2)
The Refine and the assumptions about x and y are superfluous: the whole point of ComplexExpand is that it assumes symbolic variables used within it are already real.
On Feb 26, 2013, at 1:09 AM, Brentt <brenttnewman@gmail.com> wrote:
> > Hello, > > I was wondering why this works > > IN[]:= Refine[Re[x + y I], Element[x , Reals] && Element[y , Reals]] > > Out[]:= x > > But this does not > > In[]:= Refine[Re[1/(x + y I)], Element[x , Reals] && Element[y , Reals]] > > Out[]:= Re[1/(x + y I)] > > > > Is there a nice built in way to get the real and imaginary parts of a > complex function? >
 Murray Eisenberg murray@math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 5491020 (H) University of Massachusetts 413 5452838 (W) 710 North Pleasant Street fax 413 5451801 Amherst, MA 010039305



