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Re: How to assume that a function is positive?

• To: mathgroup at smc.vnet.net
• Subject: [mg114329] Re: How to assume that a function is positive?
• From: "Kevin J. McCann" <Kevin.McCann at umbc.edu>
• Date: Wed, 1 Dec 2010 02:11:44 -0500 (EST)
• References: <id2emr$d88$1@smc.vnet.net>

How about

(f[x + y]^2)^(1/2)//PowerExpand

Kevin

On 11/30/2010 4:04 AM, Sam Takoy wrote:
> Hi,
>
> Who do I let Mathematica know that a function f is positive for all
> arguments? For example, how do I make the following work (I think my
> intention is clear):
>
> Assuming[f[x]>  0, (f[x + y]^2)^(1/2) // Simplify]
>
> Many thanks in advance,
>
> Sam
>
>