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Re: Q: ArcTan[ Tan[ x ] ] = x

• To: mathgroup at christensen.cybernetics.net
• Subject: [mg1963] Re: Q: ArcTan[ Tan[ x ] ] = x
• From: Scott.A.Hill at williams.edu (Lancelot)
• Date: Sun, 27 Aug 1995 23:24:10 -0400
• Organization: Williams College, Williamstown MA

In article <DDuMDu.Joy at wri.com>,
Ron Elsner <elsner at avalon.msfc.nasa.gov> wrote:
>Suppose I really want Mma to set ArcTan[ Tan[ x ] ] = x, or 
>ArcSin[ Sin[ x ] ] = x.  How do I do this?

Unprotect[Tan,ArcTan];
ArcTan[Tan[x_]]:=x;
Protect[Tan,ArcTan];

	will do it for the first example.  Beware however, as changing
predefined definitions like that can sometimes unpredictable
consequences....

/
:@-) Scott
\