I doubt it will give a usable result. I transformed to polar because that made the expressions more tractable; this involves also making new variables for sine and cosine, and adding the usual identity to link those algebraically. Found there are four solutions and they are huge. For better control over the process I used GroebnerBasis
directly, then used Roots
to solve for the radial variable, and back-substituted to get the sine and cosine solution for the angular variable (there is one per radial solution).
e1 = {- xa +
1/2*(\[Rho]*xd + \[Alpha]*
Sqrt[(xd^2) + (
yd^2) ] + (\[Lambda]^2*(xd^2 +
yd^2)*(\[Rho]*xd + \[Alpha]*
Sqrt[(xd^2) + (yd^2) ]))/((\[Rho]* xd + \[Alpha]*
Sqrt[(xd^2) + (yd^2) ])^2 + (\[Rho]* yd + \[Beta]*
Sqrt[(xd^2) + (yd^2) ])^2)),
-ya + 1/
2*(\[Rho]*yd + \[Beta]*
Sqrt[(xd^2) + (
yd^2) ] - (\[Lambda]^2*(xd^2 +
yd^2)*(\[Rho]*yd + \[Beta]*
Sqrt[(xd^2) + (yd^2) ]))/((\[Rho]* xd + \[Alpha]*
Sqrt[(xd^2) + (yd^2) ])^2 + (\[Rho]* yd + \[Beta]*
Sqrt[(xd^2) + (yd^2) ])^2))};
e2 = e1 /. {(xd^2 + yd^2) -> r^2, Sqrt[(xd^2) + (yd^2) ] -> r};
e3 = Join[
Together[
e2 /. {xd -> r*ctheta, yd -> r*stheta}], {ctheta^2 + stheta^2 -
1}];
Timing[gb =
GroebnerBasis[e3, {ctheta, stheta, r},
CoefficientDomain -> RationalFunctions];]
(* Out[57]= {2.448772, Null} *)
radii = Solve[gb[[1]] == 0, r, Quartics -> False];
gb2 = Rest[gb] /. radii[[1]];
sin = Solve[gb2[[1]] == 0, stheta];
cos = Solve[gb2[[2]] == 0, ctheta];
As I wrote, this is probably too large to be useful. And there are three others; which is "correct" could vary with parameter values, including the specific values of xa
and ya
.
In[82]:= radii[[1]]
(* Out[82]= {r ->
Root[16 xa^4 \[Alpha]^4 + 32 xa^2 ya^2 \[Alpha]^4 +
16 ya^4 \[Alpha]^4 + 32 xa^4 \[Alpha]^2 \[Beta]^2 +
64 xa^2 ya^2 \[Alpha]^2 \[Beta]^2 +
32 ya^4 \[Alpha]^2 \[Beta]^2 + 16 xa^4 \[Beta]^4 +
32 xa^2 ya^2 \[Beta]^4 + 16 ya^4 \[Beta]^4 -
16 xa^4 \[Alpha]^2 \[Rho]^2 - 32 xa^2 ya^2 \[Alpha]^2 \[Rho]^2 -
16 ya^4 \[Alpha]^2 \[Rho]^2 - 16 xa^4 \[Beta]^2 \[Rho]^2 -
32 xa^2 ya^2 \[Beta]^2 \[Rho]^2 -
16 ya^4 \[Beta]^2 \[Rho]^2 + (-32 xa^3 \[Alpha]^5 -
32 xa ya^2 \[Alpha]^5 - 32 xa^2 ya \[Alpha]^4 \[Beta] -
32 ya^3 \[Alpha]^4 \[Beta] - 64 xa^3 \[Alpha]^3 \[Beta]^2 -
64 xa ya^2 \[Alpha]^3 \[Beta]^2 -
64 xa^2 ya \[Alpha]^2 \[Beta]^3 -
64 ya^3 \[Alpha]^2 \[Beta]^3 - 32 xa^3 \[Alpha] \[Beta]^4 -
32 xa ya^2 \[Alpha] \[Beta]^4 - 32 xa^2 ya \[Beta]^5 -
32 ya^3 \[Beta]^5 - 32 xa^3 \[Alpha]^3 \[Lambda]^2 -
32 xa ya^2 \[Alpha]^3 \[Lambda]^2 +
32 xa^2 ya \[Alpha]^2 \[Beta] \[Lambda]^2 +
32 ya^3 \[Alpha]^2 \[Beta] \[Lambda]^2 -
32 xa^3 \[Alpha] \[Beta]^2 \[Lambda]^2 -
32 xa ya^2 \[Alpha] \[Beta]^2 \[Lambda]^2 +
32 xa^2 ya \[Beta]^3 \[Lambda]^2 +
32 ya^3 \[Beta]^3 \[Lambda]^2 + 48 xa^3 \[Alpha]^3 \[Rho]^2 +
48 xa ya^2 \[Alpha]^3 \[Rho]^2 +
48 xa^2 ya \[Alpha]^2 \[Beta] \[Rho]^2 +
48 ya^3 \[Alpha]^2 \[Beta] \[Rho]^2 +
48 xa^3 \[Alpha] \[Beta]^2 \[Rho]^2 +
48 xa ya^2 \[Alpha] \[Beta]^2 \[Rho]^2 +
48 xa^2 ya \[Beta]^3 \[Rho]^2 + 48 ya^3 \[Beta]^3 \[Rho]^2 +
16 xa^3 \[Alpha] \[Lambda]^2 \[Rho]^2 +
16 xa ya^2 \[Alpha] \[Lambda]^2 \[Rho]^2 -
16 xa^2 ya \[Beta] \[Lambda]^2 \[Rho]^2 -
16 ya^3 \[Beta] \[Lambda]^2 \[Rho]^2 -
16 xa^3 \[Alpha] \[Rho]^4 - 16 xa ya^2 \[Alpha] \[Rho]^4 -
16 xa^2 ya \[Beta] \[Rho]^4 -
16 ya^3 \[Beta] \[Rho]^4) #1 + (24 xa^2 \[Alpha]^6 +
8 ya^2 \[Alpha]^6 + 32 xa ya \[Alpha]^5 \[Beta] +
56 xa^2 \[Alpha]^4 \[Beta]^2 + 40 ya^2 \[Alpha]^4 \[Beta]^2 +
64 xa ya \[Alpha]^3 \[Beta]^3 +
40 xa^2 \[Alpha]^2 \[Beta]^4 + 56 ya^2 \[Alpha]^2 \[Beta]^4 +
32 xa ya \[Alpha] \[Beta]^5 + 8 xa^2 \[Beta]^6 +
24 ya^2 \[Beta]^6 + 48 xa^2 \[Alpha]^4 \[Lambda]^2 +
16 ya^2 \[Alpha]^4 \[Lambda]^2 +
32 xa^2 \[Alpha]^2 \[Beta]^2 \[Lambda]^2 -
32 ya^2 \[Alpha]^2 \[Beta]^2 \[Lambda]^2 -
16 xa^2 \[Beta]^4 \[Lambda]^2 -
48 ya^2 \[Beta]^4 \[Lambda]^2 +
24 xa^2 \[Alpha]^2 \[Lambda]^4 +
8 ya^2 \[Alpha]^2 \[Lambda]^4 -
32 xa ya \[Alpha] \[Beta] \[Lambda]^4 +
8 xa^2 \[Beta]^2 \[Lambda]^4 +
24 ya^2 \[Beta]^2 \[Lambda]^4 - 52 xa^2 \[Alpha]^4 \[Rho]^2 -
20 ya^2 \[Alpha]^4 \[Rho]^2 -
64 xa ya \[Alpha]^3 \[Beta] \[Rho]^2 -
72 xa^2 \[Alpha]^2 \[Beta]^2 \[Rho]^2 -
72 ya^2 \[Alpha]^2 \[Beta]^2 \[Rho]^2 -
64 xa ya \[Alpha] \[Beta]^3 \[Rho]^2 -
20 xa^2 \[Beta]^4 \[Rho]^2 - 52 ya^2 \[Beta]^4 \[Rho]^2 -
40 xa^2 \[Alpha]^2 \[Lambda]^2 \[Rho]^2 -
8 ya^2 \[Alpha]^2 \[Lambda]^2 \[Rho]^2 +
8 xa^2 \[Beta]^2 \[Lambda]^2 \[Rho]^2 +
40 ya^2 \[Beta]^2 \[Lambda]^2 \[Rho]^2 -
4 xa^2 \[Lambda]^4 \[Rho]^2 - 4 ya^2 \[Lambda]^4 \[Rho]^2 +
32 xa^2 \[Alpha]^2 \[Rho]^4 + 16 ya^2 \[Alpha]^2 \[Rho]^4 +
32 xa ya \[Alpha] \[Beta] \[Rho]^4 +
16 xa^2 \[Beta]^2 \[Rho]^4 + 32 ya^2 \[Beta]^2 \[Rho]^4 +
8 xa^2 \[Lambda]^2 \[Rho]^4 - 8 ya^2 \[Lambda]^2 \[Rho]^4 -
4 xa^2 \[Rho]^6 - 4 ya^2 \[Rho]^6) #1^2 + (-8 xa \[Alpha]^7 -
8 ya \[Alpha]^6 \[Beta] - 24 xa \[Alpha]^5 \[Beta]^2 -
24 ya \[Alpha]^4 \[Beta]^3 - 24 xa \[Alpha]^3 \[Beta]^4 -
24 ya \[Alpha]^2 \[Beta]^5 - 8 xa \[Alpha] \[Beta]^6 -
8 ya \[Beta]^7 - 24 xa \[Alpha]^5 \[Lambda]^2 -
8 ya \[Alpha]^4 \[Beta] \[Lambda]^2 -
16 xa \[Alpha]^3 \[Beta]^2 \[Lambda]^2 +
16 ya \[Alpha]^2 \[Beta]^3 \[Lambda]^2 +
8 xa \[Alpha] \[Beta]^4 \[Lambda]^2 +
24 ya \[Beta]^5 \[Lambda]^2 - 24 xa \[Alpha]^3 \[Lambda]^4 +
8 ya \[Alpha]^2 \[Beta] \[Lambda]^4 +
8 xa \[Alpha] \[Beta]^2 \[Lambda]^4 -
24 ya \[Beta]^3 \[Lambda]^4 - 8 xa \[Alpha] \[Lambda]^6 +
8 ya \[Beta] \[Lambda]^6 + 24 xa \[Alpha]^5 \[Rho]^2 +
24 ya \[Alpha]^4 \[Beta] \[Rho]^2 +
48 xa \[Alpha]^3 \[Beta]^2 \[Rho]^2 +
48 ya \[Alpha]^2 \[Beta]^3 \[Rho]^2 +
24 xa \[Alpha] \[Beta]^4 \[Rho]^2 +
24 ya \[Beta]^5 \[Rho]^2 +
32 xa \[Alpha]^3 \[Lambda]^2 \[Rho]^2 -
32 ya \[Beta]^3 \[Lambda]^2 \[Rho]^2 +
8 xa \[Alpha] \[Lambda]^4 \[Rho]^2 +
8 ya \[Beta] \[Lambda]^4 \[Rho]^2 -
24 xa \[Alpha]^3 \[Rho]^4 -
24 ya \[Alpha]^2 \[Beta] \[Rho]^4 -
24 xa \[Alpha] \[Beta]^2 \[Rho]^4 -
24 ya \[Beta]^3 \[Rho]^4 -
8 xa \[Alpha] \[Lambda]^2 \[Rho]^4 +
8 ya \[Beta] \[Lambda]^2 \[Rho]^4 + 8 xa \[Alpha] \[Rho]^6 +
8 ya \[Beta] \[Rho]^6) #1^3 + (\[Alpha]^8 +
4 \[Alpha]^6 \[Beta]^2 + 6 \[Alpha]^4 \[Beta]^4 +
4 \[Alpha]^2 \[Beta]^6 + \[Beta]^8 +
4 \[Alpha]^6 \[Lambda]^2 +
4 \[Alpha]^4 \[Beta]^2 \[Lambda]^2 -
4 \[Alpha]^2 \[Beta]^4 \[Lambda]^2 -
4 \[Beta]^6 \[Lambda]^2 + 6 \[Alpha]^4 \[Lambda]^4 -
4 \[Alpha]^2 \[Beta]^2 \[Lambda]^4 +
6 \[Beta]^4 \[Lambda]^4 + 4 \[Alpha]^2 \[Lambda]^6 -
4 \[Beta]^2 \[Lambda]^6 + \[Lambda]^8 -
4 \[Alpha]^6 \[Rho]^2 - 12 \[Alpha]^4 \[Beta]^2 \[Rho]^2 -
12 \[Alpha]^2 \[Beta]^4 \[Rho]^2 - 4 \[Beta]^6 \[Rho]^2 -
8 \[Alpha]^4 \[Lambda]^2 \[Rho]^2 +
8 \[Beta]^4 \[Lambda]^2 \[Rho]^2 -
4 \[Alpha]^2 \[Lambda]^4 \[Rho]^2 -
4 \[Beta]^2 \[Lambda]^4 \[Rho]^2 + 6 \[Alpha]^4 \[Rho]^4 +
12 \[Alpha]^2 \[Beta]^2 \[Rho]^4 + 6 \[Beta]^4 \[Rho]^4 +
4 \[Alpha]^2 \[Lambda]^2 \[Rho]^4 -
4 \[Beta]^2 \[Lambda]^2 \[Rho]^4 - 2 \[Lambda]^4 \[Rho]^4 -
4 \[Alpha]^2 \[Rho]^6 -
4 \[Beta]^2 \[Rho]^6 + \[Rho]^8) #1^4 &, 1]} *)