Re: List of solution
- To: mathgroup at smc.vnet.net
- Subject: [mg47023] Re: List of solution
- From: "Dana DeLouis" <delouis at bellsouth.net>
- Date: Sat, 20 Mar 2004 03:50:35 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Hello. Here is a little function that I use. I use RealsOnly vs the
built in package RealOnly.
RealsOnly[v_List] := Drop[v, Union[First /@ Position[(#1[[All,2]] & ) /@
v, _Complex, Infinity]]]
Generate some data?
sol = NSolve[{(x + y)^4 + (x + y)^2 == 3, 4*x - 2*y == 4}];
When doing it this way, some Complex numbers appear to fall thru the
crack.
Select[sol, FreeQ[#1, I] & ]
{{x -> 0.28620267541797006, y -> -1.4275946491640596},
{x -> 1.0471306579153632, y -> 0.09426131583072653},
{x -> 0.6666666666666666 - 0.5058299711839932*I,
y -> -0.6666666666666666 - 1.0116599423679864*I}}
However, by scanning all positions for Complex Numbers, it seems to work
ok.
RealsOnly[sol]
{{x -> 0.28620267541797006, y -> -1.4275946491640596},
{x -> 1.0471306579153632, y -> 0.09426131583072653}}
HTH.
--
Dana DeLouis
Windows XP
Mathematica 5.0 for Windows
delouis at bellsouth.net
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"Clément" <rusheraquatic at ifrance.com> wrote in message
news:c3bgf6$7qh$1 at smc.vnet.net...
> Hello MathGroup,
>
> I have resolved an equation. So i have a list of solution like :
> {{x->0,
> y->0}{x->1, y->0}{x->i, y->1+2i}}
> I want to remove the complex solutions of this list.
> How can i do ?
>
> Thanks