Re: get a, b from numbers in the form a+b Pi
- To: mathgroup at smc.vnet.net
- Subject: [mg119210] Re: get a, b from numbers in the form a+b Pi
- From: Peter Breitfeld <phbrf at t-online.de>
- Date: Wed, 25 May 2011 05:56:01 -0400 (EDT)
- References: <irfvf7$bs8$1@smc.vnet.net>
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