Re: Re: differentiation operator

*To*: mathgroup at smc.vnet.net*Subject*: [mg100719] Re: [mg100662] Re: differentiation operator*From*: Murray Eisenberg <murray at math.umass.edu>*Date*: Thu, 11 Jun 2009 21:43:06 -0400 (EDT)*Organization*: Mathematics & Statistics, Univ. of Mass./Amherst*References*: <h0nulh$be1$1@smc.vnet.net> <200906102110.RAA00562@smc.vnet.net>*Reply-to*: murray at math.umass.edu

That works reasonable well. For example, all the following forms work OK (in the last form I simulate the Mathematica 2D standard form): d/dx Sin[x] (d/dx) Sin[x] (d Sin[x])/dx d -- Sin[x] dx However, what does NOT work as one might hope is... d Sin[x]/x ...even though that is a perfectly acceptable, traditional (with a small "t") mathematical form for the same derivative. Of course the use of the d/dx ties everything to a particular variable. Change from x to y or t or something else, and it's dead. dh wrote: > Hi Chee, > > I did not thoroughly test it, but if you define: > > $Pre = # /. Times[ d expr_ Power[dx, -1]] :> D[expr, x] & > > the following examples work: > > d/dx x^2 -> 2x > > d/dx Sin[x] -> Cos[x] > > d/dx (x-x^3) -> 1-3x^2 > > e.t.c > > Daniel > > > > Chee Lim Cheung wrote: > >> Hi All > > >> My students have asked me whether it is possible to define the operator > >> df[x]/dx for differentiation rather than D[f[x],x]. The operator is > >> available in a palette but it does not seem to do anything other than for > >> display only. > > >> Example: d/dx(x^2)=2x rather than D[x^2,x]=2x. > > >> Am I missing something? > > >> Thanks > >> Mr. Chee > > > > -- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305

**References**:**Re: differentiation operator***From:*dh <dh@metrohm.com>