Re: get a, b from numbers in the form a+b Pi
- To: mathgroup at smc.vnet.net
- Subject: [mg119168] Re: get a, b from numbers in the form a+b Pi
- From: Wolfgang Windsteiger <Wolfgang.Windsteiger at risc.jku.at>
- Date: Mon, 23 May 2011 06:28:22 -0400 (EDT)
- References: <iraq88$ls8$1@smc.vnet.net>
Dear Rob, if I understand correctly what you want, then I would suggest Cases[Expand[nums], a_ + b_*Pi -> {a, b}] It first expands all numbers to make sure that no factored forms occur anymore. Then find all the cases of the form a_ + b_*Pi (which are *all* in this example), and give back {a,b} instead of the matched a_ + b_*Pi number. Hope that is what you were aiming for. Ciao, WW. On 05/22/2011 12:58 PM, 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