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MathGroup Archive 2006

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Re: mapping of function

  • To: mathgroup at smc.vnet.net
  • Subject: [mg69961] Re: mapping of function
  • From: Peter Pein <petsie at dordos.net>
  • Date: Thu, 28 Sep 2006 06:16:02 -0400 (EDT)
  • References: <efdjnn$ms$1@smc.vnet.net>

dimmechan at yahoo.com schrieb:
> Hello.
> 
> I am working on John Gray's Book Mastering Mathematica.
> 
> Here is one simple expression.
> 
> exp1 = x^3 + (1 + z)^2
> x^3 + (1 + z)^2
> 
> I am thinking of ways to map the sine function only to {x,z}.
> Here are some alternatives I considered.
> 
> MapAt[Sin, exp1, Flatten[(Position[exp1, #1] & ) /@ Variables[exp1],
> 1]]
> Sin[x]^3 + (1 + Sin[z])^2
> 
> MapAt[Sin, exp1, Position[exp1, _Symbol, Heads -> False]]
> Sin[x]^3 + (1 + Sin[z])^2
> 
> Are there any other possibilities?
> 
> Thanks for any response.
> 

Hi,

the following is not mapping, but IMHO it does the same in a very simple 
way:

In[1]:= exp1 = x^3 + (1 + z)^2;
In[2]:= exp1 /. v: x | z :> Sin[v]
Out[2]= Sin[x]^3 + (1 + Sin[z])^2

or more general:

In[3]:= exp1 /. v:Alternatives @@ Variables[exp1] :> Sin[v]
Out[3]= Sin[x]^3 + (1 + Sin[z])^2

Peter


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