MathGroup Archive: January 2003 [00282]

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Prefix[f[x]], why is it not working

To: mathgroup at smc.vnet.net
Subject: [mg38909] Prefix[f[x]], why is it not working
From: "Ashraf El Ansary" <Elansary at btopenworld.com>
Date: Sat, 18 Jan 2003 00:38:44 -0500 (EST)
Sender: owner-wri-mathgroup at wolfram.com

Hi all,
Does anyone why f@a_=2 a gives a proper answer for f[1]
and not in the case of Prefix[s[a_]]= 2 a eventhough that Prefix[s[a_]]=
f@a_???

Thanks
In[1]:=
f@a_=2 a
f[1]
Out[1]=
2 a
Out[2]=
2
In[3]:=
Prefix[s[a_]]
Prefix[s[a_]]=2 a
s[1]
Out[3]=
s@a_
Set::write: Tag Prefix in s@a_ is Protected.
Out[4]=
2 a
Out[5]=
s[1]

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