Re: rookie code issue
- To: mathgroup at smc.vnet.net
- Subject: [mg130212] Re: rookie code issue
- From: Bill Rowe <readnews at sbcglobal.net>
- Date: Thu, 21 Mar 2013 00:55:29 -0400 (EDT)
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- Delivered-to: l-mathgroup@wolfram.com
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On 3/20/13 at 4:22 AM, robholman at gmail.com wrote:
>Why doesn't the following code return a 2?
>m = Cos; Which[m == Sin, 5, m == Cos, 2]
Notice
In[3]:= Head /@ {Cos, Sin}
Out[3]= {Symbol,Symbol}
So, by using Equal, you are asking Mathematica to determine
whether two symbols without assigned values are equal which it
cannot do.
What you want to use here is SameQ rather than Equal. That is
In[4]:= m = Cos;
Which[m === Sin, 5, m === Cos, 2]
Out[5]= 2