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Re: "Nice" complex form

• To: mathgroup at smc.vnet.net
• Subject: [mg131597] Re: "Nice" complex form
• From: Bob Hanlon <hanlonr357 at gmail.com>
• Date: Tue, 10 Sep 2013 03:34:07 -0400 (EDT)
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• References: <20130909040609.9789D6A14@smc.vnet.net>

The form that you are seeking is not "simpler" so you would need to force
it.


(expr1 = Sqrt[a - 4]) // LeafCount


7


expr2 = expr1 /. Sqrt[x_] -> I Sqrt[-x]


I*Sqrt[4 - a]


expr2 // LeafCount


13


Simplify[expr1 == expr2, a - 4 < 0]


True



Bob Hanlon




On Mon, Sep 9, 2013 at 12:06 AM, <sam.takoy at yahoo.com> wrote:

> Hi,
>
> Can I get
>
> Assuming[a - 4 < 0, Sqrt[a - 4]]
>
> to "simplify" to
>
> I Sqrt[4 - a]
>
> ?
>
> Thanks,
>
> Sam
>
>
>

• References:
  • "Nice" complex form
    • From: sam.takoy@yahoo.com