Groups > comp.soft-sys.math.mathematica > #2653

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

From	Murray Eisenberg <murray@math.umass.edu>
Newsgroups	comp.soft-sys.math.mathematica
Subject	Re: get a, b from numbers in the form a+b Pi
Date	2011-05-23 10:23 +0000
Organization	Steven M. Christensen and Associates, Inc and MathTensor, Inc.
Message-ID	<irdcij$3jr$1@smc.vnet.net> (permalink)

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I forgot that you wanted only the a and the b, not the Pi. The following 
will do what you want -- again only in the case that both a and b are 
nonzero:

   Through[{First, (Last[#]/Pi &)}[#]] & /@ Expand[nums]

On 5/22/2011 6:57 AM, 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

-- 
Murray Eisenberg                     murray@math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305

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Re: get a, b from numbers in the form a+b Pi Murray Eisenberg <murray@math.umass.edu> - 2011-05-23 10:23 +0000

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