Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.soft-sys.math.mathematica > #16428 > unrolled thread

Re: Simple question

Back to article view | Back to comp.soft-sys.math.mathematica

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  Re: Simple question Bob Hanlon <hanlonr357@gmail.com> - 2014-01-16 06:52 +0000

#16428 — Re: Simple question

Actually you do want to use ReplaceAll, you just don't want to manually
enumerate all of the rules.


expr = K11 Ue + (K12 - K21) Uex + K22 Uexx +
   (K23 + K32) Uexy + (K13 - K31) Uey + K33 Ueyy;


expr2 = expr /. ((# -> D[U[x, y, z, t],
        Sequence @@ (ToExpression@
           Characters@StringDrop[ToString@#, 2])]) & /@
    Select[Variables[expr],
     StringMatchQ[ToString[#], "Ue*"] &])



Bob Hanlon




On Wed, Jan 15, 2014 at 4:16 AM, KFUPM <hussain.alqahtani@gmail.com> wrote:

> Dear  All
>
> I have a long expression. Below is just a short part of it:
>
> K11 Ue + (K12 - K21) Uex +
>  K22 Uexx + (K23 + K32) Uexy + (K13 - K31) Uey + K33 Ueyy
>
> I want to replace Ue->U[x,y,z,t]. and Uex->D[U[x,y,z,t],x] and
> Uexy->D[U[x,y,z,t],{x,y}] and so on. I want to make a command to scan the
> expression and do the conversion autmatically. I don't want to use Replace
> or ReplaceAll commands, because as I said, the command is very long and I
> have so many functions to deal with.
>
> Many thanks in advance for your help.
>
> HMQ
>
>

[toc] | [standalone]

Back to top | Article view | comp.soft-sys.math.mathematica

csiph-web