Re: get a, b from numbers in the form a+b Pi
- To: mathgroup at smc.vnet.net
- Subject: [mg119167] Re: get a, b from numbers in the form a+b Pi
- From: Albert Retey <awnl at gmx-topmail.de>
- Date: Mon, 23 May 2011 06:28:11 -0400 (EDT)
- References: <iraq88$ls8$1@smc.vnet.net>
Hi, > 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 I was surprised that CoefficientList does work with Pi as a variable, which makes the whole task as simple as: CoefficientList[#, Pi] & /@ nums hth, albert