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MathGroup Archive 2005

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Re: Absolute value of a symbolic complex expression

  • To: mathgroup at smc.vnet.net
  • Subject: [mg62198] Re: [mg62190] Absolute value of a symbolic complex expression
  • From: "David Park" <djmp at earthlink.net>
  • Date: Mon, 14 Nov 2005 00:38:43 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

1) You must use capital I for the unit imaginary instead of small i.

2) Then use ComplexExpand, your best friend in working with complex
expressions. You will also sometimes want to use the TargetFunctions option.

Abs[a + I b]
ComplexExpand[%]

giving..


Abs[a + I*b]
Sqrt[a^2 + b^2]

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/

From: mailcwc at gmail.com [mailto:mailcwc at gmail.com]
To: mathgroup at smc.vnet.net


I have a long complex equation with all symbols real. How do I get the
Abs of that equation.
For example, Abs[a + i b] =Sqrt[a^2 +b^2]



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