Re: Finding real part (newbie question)
- To: mathgroup at smc.vnet.net
- Subject: [mg15762] Re: Finding real part (newbie question)
- From: Stephen P Luttrell <luttrell at signal.dra.hmg.gb>
- Date: Sun, 7 Feb 1999 02:03:45 -0500 (EST)
- Organization: Defence Evaluation and Research Agency
- References: <79e8lo$9du@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
>If a,b,c,d are real numbers. How do I use mathematica to find the real
>part of
>
>1/(a + I b + 1/(c + I d))
>
>Yes I can calculate it by hand, but I would like to know how to use
>Mathematica.
This should do what you want:
In[1]:=ComplexExpand[1/(a + I b + 1/(c + I d)),TargetFunctions->{Re,Im}]
Out[1]=a/((a + c/(c^2 + d^2))^2 + (b - d/(c^2 + d^2))^2) -
(I*b)/((a + c/(c^2 + d^2))^2 + (b - d/(c^2 + d^2))^2) +
c/((c^2 + d^2)*((a + c/(c^2 + d^2))^2 +
(b - d/(c^2 + d^2))^2)) +
(I*d)/((c^2 + d^2)*((a + c/(c^2 + d^2))^2 +
(b - d/(c^2 + d^2))^2))
Check ComplexExpand in the Help Browser for more information.
Stephen P Luttrell
Signal Processing and Imagery Department DERA Malvern, St.Andrew's Road
Malvern, United Kingdom, WR14 3PS
+44 (0)1684 894046 (tel)
+44 (0)1684 894384 (fax)
luttrell at signal.dera.gov.uk (email)