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simple problem with Map?!?

• To: mathgroup at smc.vnet.net
• Subject: [mg49480] simple problem with Map?!?
• From: relishguy at pluggedin.org (Relishguy)
• Date: Wed, 21 Jul 2004 06:40:32 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

I do not understand why the last evaluation ends up screwed:

In[1]:= d0 = {30,60,180,60,30};

In[2]:= tt = Plus @@ d0
Out[2]= 360

In[3]:= pp = N[d0 / tt]
Out[3]= {0.0833333,0.166667,0.5,0.166667,0.0833333}

In[4]:= ppp = N[d0 / (Plus @@ d0)]
Out[4]= {0.0833333,0.166667,0.5,0.166667,0.0833333}

In[5]:= pppp = N[# / (Plus @@ #)]& /@ d0
Out[5]= {1.,1.,1.,1.,1.}

Can anyone explain this simply? Do I need Hold[] or Evaluate[] somewhere?

TIA.

Regards..

• Follow-Ups:
  • Re: simple problem with Map?!?
    • From: DrBob <drbob@bigfoot.com>
  • Re: simple problem with Map?!?
    • From: Andrzej Kozlowski <akoz@mimuw.edu.pl>