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Re: slot argument weirdness

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  • Subject: [mg83995] Re: slot argument weirdness
  • From: Jerry <JLK2941 at>
  • Date: Thu, 6 Dec 2007 02:48:02 -0500 (EST)
  • References: <fj37b2$hok$>

Thanks to all that responded, this really helps.

Even though I've made lots of attempts to understand what 
pure functions are and how to use them, I'm still not there. 
Some examples seem so clear but virtually every time I try 
to do it myself, I find I haven't caught the idea. And I've 
read thru all the HELP and tutorials! I'll keep trying. 
Thanks again.

Jerry wrote:
> I have to produce some bulky matrices which are described by 
> two parameters and it seems the easiest way to produce them 
> is as follows (I took out all the complexity and just left 
> in the slots to illustrate my problem). v is the parameter 
> array.
> v = {2, 5};
> myMatrix=Apply[{{#1, #2}, {#2, #1}} &, v]
> giving     {{2, 5}, {5, 2}}    and all is well.
> But since the actual form in the first argument in Apply is 
> really a large messy thing, I thought I'd produce it just 
> once in the notebook and represent it with:
> m = {{#1, #2}, {#2, #1}};
> But geez, this doesn't work at all:
> MyMatrix2= Apply[m &, v]
> gives      {{#1, #2}, {#2, #1}}
> I've tried a lot of things to make this work but have failed 
> completely. If someone can tell me that there is absolutely 
> no representation of the slot configuration that will do 
> what I want, then I can quit trying. Or is there? Thanks for 
> any info.

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