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Re: get a, b from numbers in the form a+b Pi

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You can expand abRule to look like this, then Pi-free numbers are
handled as well:

abRule ={a_. +b_. Pi :>{a,b}, x_?NumberQ:>{x,0}}


Murray Eisenberg wrote:

> The code fails to give a pair {a,b} in case the list nums includes a 
> Pi-free number, e.g., 2.
>
>
> On 5/23/2011 6:28 AM, Peter Breitfeld wrote:
>> "1.156" wrote:
>>
>>> I have lists  of numbers (Mathematica output) all numerically in the
>>> form a + b*Pi and I'm trying to extract the values of a and b for
>>> further work.
>>>
>>> Here's an example of the best I've been able to do so far:
>>>
>>> nums={1/2 (-2+\[Pi]),-2+(3 \[Pi])/4,-(11/3)+(5 \[Pi])/4,5/48 (-64+21
>>> \[Pi]),-(61/5)+(63 \[Pi])/16,-(338/15)+(231 \[Pi])/32};
>>> {FullForm[#][[1,1]],FullForm[#][[1,2]]/\[Pi]}&/@nums
>>>
>>> When I run this line of code 4 of the six input numbers give me the
>>> {a,b} I'm looking for but the first and fourth entries fail because the
>>> form isn't right. Possibly I could patch this scheme to look for a small
>>> finite set of possibilities of input number form but I suspect I may a
>>> long way from attacking this problem correctly.
>>>
>>> Can someone offer some other ideas on how to pull this off? Many thanks
>>> for looking at this. Rob
>>> --
>>> Sent from my plain desktop PC.
>>>
>>
>> Try this:
>>
>> abRule = a_. + b_. Pi :>  {a, b}
>> Expand[nums]
>> % /. abRule


-- 
_________________________________________________________________
Peter Breitfeld, Bad Saulgau, Germany -- http://www.pBreitfeld.de

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Re: get a, b from numbers in the form a+b Pi Murray Eisenberg <murray@math.umass.edu> - 2011-05-24 09:57 +0000
  Re: get a, b from numbers in the form a+b Pi Peter Breitfeld <phbrf@t-online.de> - 2011-05-25 09:56 +0000

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