Q: How to replace...
- To: mathgroup at smc.vnet.net
- Subject: [mg9695] Q: How to replace...
- From: Halldor Bjornsson <hbjorn1 at po-box.mcgill.ca>
- Date: Fri, 21 Nov 1997 01:31:33 -0500
- Organization: McGill University
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
This is probably an elementary question:
I am manipulating differential equations, and am having trouble with
getting Mathematica to stop evaluating everything fully.
A trivial example of my problem is the following:
In[1]: = z[x_]=Exp[2 x];
In[2]:= dz=D[z[x],x]
Out[2]= 2 Exp[2x]
If I want to write this as "dz=2 z[x]" and do
dz /. {Exp[2] -> z[x]}
I will still get 2 Exp[2x] out since z[x] is evaluated after the
replacement. Delayed replacement (" :>" does not seem to help.
Anyone know how to replace without evaluation ?
Thanks for your help
Halldor