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MathGroup Archive 2013

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Re: how to set initial values to symbolic variable array?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg129973] Re: how to set initial values to symbolic variable array?
  • From: Tomas Garza <tgarza10 at msn.com>
  • Date: Thu, 28 Feb 2013 21:28:02 -0500 (EST)
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  • References: <20130228044555.115C46877@smc.vnet.net>

Perhaps something like this:
In[1]:= Clear[a,r]
In[2]:= Array[a,4]
Out[2]= {a[1],a[2],a[3],a[4]}
In[3]:= f=a[1]+a[2]+a[3]+a[4]
Out[3]= a[1]+a[2]+a[3]+a[4]
In[4]:= r=Table[a[j]->1,{j,1,4}]
Out[4]= {a[1]->1,a[2]->1,a[3]->1,a[4]->1}
In[5]:= f/.r
Out[5]= 4
-Tomas

> From: devout1977 at gmail.com
> Subject: how to set initial values to symbolic variable array?
> To: mathgroup at smc.vnet.net
> Date: Wed, 27 Feb 2013 23:45:55 -0500
>
>
> Dear All,
>
> Suppose I defined a symbolic variable array as
>
> Array[a,4]
>
> and defined a function as
>
> f = a[1] + a[2] + a[3] + a[4]
>
> I need to evaluate the value of f in the following way,
>
> f/.{a[1]->1,a[2]->1, ...}
>
> but specify each element of the array one by one is very troublesome, and I
> wonder whether there is something like a group definition like
>
> f/.{a[1:4]->1}
>
> to define the four variables at the same time with the same value.
>
> Thanks for your help,
>
> Sincerely,
> John
>
>



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