Re: Outer with index in bounds

• To: mathgroup at smc.vnet.net
• Subject: [mg80451] Re: Outer with index in bounds
• From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
• Date: Thu, 23 Aug 2007 00:57:11 -0400 (EDT)
• Organization: The Open University, Milton Keynes, UK
• References: <fagu1f\$92b\$1@smc.vnet.net>

```DC wrote:

> Hi all, I would like to use Outer as:
>
> Outer[f[#1,#2]&,Range[10],Range[#1],1,1]
>
> in order to create a list whose first element is a list of length 1, the
> second is a list of length 2, and so on.
> More generally, I would like to use Outer with one bound depending on
> the other as in :
>
> Outer[f[#1,#2]&,list1,list2[#1],1,1]
>
> Obviously none of the above works.

Note that your original expressions are missing one '&' character.
Moreover, *Outer* does not pass any parameter to its second argument
onwards. So, assuming I have correctly understood what you want, the
following will do it:

In[1]:= Outer[f[#1, #2] &, Range[3], Range[#1], 1, 1] & /@ Range[3]

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

--
Jean-Marc

```

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