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Re: Maen

  • To: mathgroup at
  • Subject: [mg48166] Re: Maen
  • From: Bill Rowe <readnewsciv at>
  • Date: Fri, 14 May 2004 20:59:51 -0400 (EDT)
  • Sender: owner-wri-mathgroup at

On 5/14/04 at 12:12 AM, per.ronne at
(Per R¯n) wrote:


>If I look up in the Stephen Wolfram's Mathematica book 5th Edition
>on page 109, it should be possible to get:

>data = {4.7, 7.2, 8.4, 5.8, 9.2, 3.9} Mean[data] 6.46667

>But instead I get:

>Mean[{4.7, 7.2, 8.4, 5.8, 9.2, 3.9}]

>What is wrong?

Mathematica returns an unevaluated function whenever it doesn't know how to evaluate it. For example, if you start a fresh session by typing

data = {4.7, 7.2, 8.4, 5.8, 9.2, 3.9}

You would get

xxx[{4.7, 7.2, 8.4, 5.8, 9.2, 3.9}]

since xxx is undefined and Mathematica doesn't know what to do.

But since Mean is a protected symbol built into the kernel starting with version 5.0 of Mathematica, I would not expect Mathematica to return an unevaluated result unless you intentionally unprotected Mean and created a new definition.

If you cut and paste

Mean[{4.7, 7.2, 8.4, 5.8, 9.2, 3.9}]

from this email into a fresh Mathematica expression then evaluate it using shift-return do you get the correct result? If the answer is yes, then there must have been something you did earlier to cause Mathematica not to evaluate Mean.

If no, have you modified the init.m file?

If you still get an unevaluated result from Mean in a fresh session with unmodified init.m files, probably the best thing to do is get in contact with Wolfram support.
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