Re: Problem with Thread over Plus?

• To: mathgroup at smc.vnet.net
• Subject: [mg65392] Re: Problem with Thread over Plus?
• From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
• Date: Thu, 30 Mar 2006 05:29:42 -0500 (EST)
• Organization: The Open University, Milton Keynes, UK
• References: <e0dsg9\$r67\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Virgilio, Vincent - SSD wrote:
> Hello,
>
> Why does this work:
>
> 	Thread[ Plus[ {1,1} , { {1,1} , {2,2} } ] ]
>
> but this doesn't?
>
> 	Thread[ Plus[ {1,1} , { {1,1} , {2,2} , {3,3} } ] ]
>
> Thanks,
>
> Vince Virgilio

As stated by the error message returned by In[1], both list must be of
equal lengths. Therefore, In[2], with three 1s rather than two, works as
expected.

In[1]:=
Thread[{1, 1} + {{1, 1}, {2, 2}, {3, 3}}]

Thread::tdlen: Objects of unequal length in {1, 1} + {{1, 1}, {2, 2},
{3, 3}} cannot be combined.

Thread::tdlen: Objects of unequal length in {1, 1} + {{1, 1}, {2, 2},
{3, 3}} cannot be combined.

Out[1]=
{1, 1} + {{1, 1}, {2, 2}, {3, 3}}

In[2]:=
Thread[{1, 1, 1} + {{1, 1}, {2, 2}, {3, 3}}]

Out[2]=
{{2, 3, 4}, {2, 3, 4}}

Regards,
JM

```

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