Re: Getting the Derivative of an HoldForm Expression

*To*: mathgroup at smc.vnet.net*Subject*: [mg127858] Re: Getting the Derivative of an HoldForm Expression*From*: nitgun at gmail.com*Date*: Tue, 28 Aug 2012 04:49:21 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net*References*: <k16jfv$bep$1@smc.vnet.net> <k1a28l$icg$1@smc.vnet.net>

Thank you for your reply. Unfortunately I made my example a bit confusing. Because actually I need the replacement the other way round. I want to replace common subexpressions. Some occur after some fancy calculations and others I can avoid by substituting right at the beginning (as my given example). That's why I want to include the terms for the replacement in the notebook as well so that others can understand the calculations. Otherwise nobody would know what a[t] stands for, unless he finds the replacement in the end. But maybe it works when I put it into such a replacement list.