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Re: How to find the index of a maximal element in a list?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg72985] Re: How to find the index of a maximal element in a list?
  • From: Bill Rowe <readnewsciv at sbcglobal.net>
  • Date: Sat, 27 Jan 2007 06:29:46 -0500 (EST)

On 1/25/07 at 6:19 AM, vsorana at yahoo.com (Valter Sorana) wrote:

>I may have a mental block, but I cannot find anything better than

>Position[listName,Max[listName]]

>that traverses the list twice - once to find the maximum and once to
>find where it is.

>Isn't there a way to get both the index and the max value in one go?

>(of course one could write a loop that does this, but I want to
>avoid loops)

Assuming you are using the current version of Mathematica (or at 
least version 4.1 and later) the function you want to use is 
Ordering, i.e.

In[9]:=
data = Table[Random[], {100}];
Ordering[data, -1]

Out[10]=
{47}

In[11]:=
Position[data, Max[data]]

Out[11]=
{{47}}
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