Re: how to replace...?
- To: mathgroup@smc.vnet.net
- Subject: [mg12443] Re: how to replace...?
- From: Carl Woll <carlw@fermi.phys.washington.edu>
- Date: Tue, 19 May 1998 13:31:15 -0400
- Organization: University of Washington
- References: <6jf035$3cu@smc.vnet.net>
Hi Yacine, One idea is to use Series. For example (f[y]-f[x])/(y-x) /. y->x + e + O[e]^2 will produce the output f'[x] + O[e] The O[e]^2 term will convert x+e into a Series expression, and then Mathematica's rules for Series produces the output shown. Carl Woll Dept of Physics U of Washington On 14 May 1998, Yacine Ait-Sahalia wrote: > Hi, > > 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? > > Thanks! > > >