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Re: Problem with SetDelayed lhs:=rhs

• To: mathgroup at smc.vnet.net
• Subject: [mg128262] Re: Problem with SetDelayed lhs:=rhs
• From: Bill Rowe <readnews at sbcglobal.net>
• Date: Sat, 29 Sep 2012 20:08:57 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• Delivered-to: l-mathgroup@wolfram.com
• Delivered-to: mathgroup-newout@smc.vnet.net
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On 9/29/12 at 2:56 AM, zahava.ginny at gmail.com wrote:

>An assignment using SetDelayed, lhs := rhs, maintains rhs in
>completely unevaluated form. Thus, if k=5, say, the assignment

>In[1] = f[k,j_]:=rhs[k,j]

You want to define f as

f[k_,j_]:= rhs[k,j]

That is you failed to include and underscore following k That is

In[1]:= f[k_, j_] := rhs[k, j]

In[2]:= f[5, j]

Out[2]= rhs(5,j)

However with your definition you could do:

In[3]:= Clear[f];
f[k, j_] := rhs[k, j]

In[5]:= k = 5;
f[k, j]

Out[6]= f(5,j)