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Disappearing variables

• To: mathgroup at smc.vnet.net
• Subject: [mg13759] Disappearing variables
• From: nobody at News.Dal.Ca
• Date: Mon, 24 Aug 1998 05:07:10 -0400
• Organization: ISINet, Nova Scotia
• Sender: owner-wri-mathgroup at wolfram.com

I want to to define a variable inside a function, as follows: f:=x=123;
Whenever I run f, x should be given the value of 123, and if x doesn't
exist, it should be created. However:

In[1]:= f:=x=123;
In[2]:=f
Out[2]:=123
In[3]:=x
Out[3]:=123        ** x exists
In[4]:=Remove[x];
In[5]:=f
Out[5]:=123  ** f seems to work 
In[6]:=x
Out[6]:=x     ** x doesn't exist anymore, even though f worked

It seems like x is created when I initially define f, whereas since f is
SetDelayed,  x should be created when I run f.  Does anyone know why x
is not created when I run f?

Vilis Nams