Re: how to replace...?
- To: mathgroup@smc.vnet.net
- Subject: [mg12484] Re: how to replace...?
- From: "Allan Hayes" <hay@haystack.demon.cc.uk>
- Date: Tue, 19 May 1998 13:31:48 -0400
- References: <6jf035$3cu@smc.vnet.net>
Yacine Ait-Sahalia, writes > What should I do to systematically replace the limit > (f[y]-f[x])/(y-x) /. y->x > by f'[x], no matter what the function f is? Yacine: Unprotect[Limit]; Limit[(f_[y_]-f_[x_])/(y_-x_), y_->x_]:= f'[x] Limit[(f[y]-f[x])/(y-x), y->x] f'[x] -- Allan Hayes Mathematica Training and Consulting Leicester UK http://www.haystack.demon.co.uk hay@haystack.demon.co.uk voice: +44 (0)116 271 4198 fax: +44(0)116 271 8642