Re: Computation does not stop when solving system quadratic eqn
- To: mathgroup at smc.vnet.net
- Subject: [mg82563] Re: Computation does not stop when solving system quadratic eqn
- From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
- Date: Thu, 25 Oct 2007 05:59:53 -0400 (EDT)
- Organization: The Open University, Milton Keynes, UK
- References: <ffmvn3$5dl$1@smc.vnet.net>
sapsi wrote:
> I have two quadratic equations in two unknowns l1 , l2. I try to solve
> it using Solve (i could do it by hand but it's quite messy and wanted
> to Mathematica to take the trouble).
>
> Solve[{32 k l2 r^2 - 16 l2^2 r^2 +
> l1^2 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
> 16 r^2) +
> k^2 (nxb^2 + nyb^2 - 2 nxb p0x + p0x^2 - 2 nyb p0y + p0y^2 -
> 16 r^2) +
> l1 (-32 l2 r^2 +
> 2 k (ax (nxb - p0x) - nxb p0x + p0x^2 + ay (nyb - p0y) -
> nyb p0y + p0y^2 - 16 r^2)) == 0,
> -d^2 l1^2 + l1 (-2 d^2 k - 2 d^2 l2) +
> k^2 (ax^2 + ay^2 - d^2 - 2 ax nxb + nxb^2 - 2 ay nyb + nyb^2) +
> l2^2 (ax^2 + ay^2 - d^2 - 2 ax p0x + p0x^2 - 2 ay p0y + p0y^2) +
> 2 k l2 (ax^2 + ay^2 - d^2 + nxb p0x - ax (nxb + p0x) + nyb p0y -
> ay (nyb + p0y)) == 0}, {l1, l2}]
>
> However, the calculation does not stop and seems to run for ever.
> Could some one please suggest any modifications i need to do?
Rewrite temporarily the coefficients of l1 and l2 in a simpler form.
In[1]:= rules = {c[1] -> 32 k l2 r^2 - 16 l2^2 r^2,
c[2] -> (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
16 r^2),
c[3] ->
k^2 (nxb^2 + nyb^2 - 2 nxb p0x + p0x^2 - 2 nyb p0y + p0y^2 -
16 r^2),
c[4] -> (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 + ay (nyb - p0y) -
nyb p0y + p0y^2 - 16 r^2)),
c[5] -> -d^2,
c[6] -> (-2 d^2 k - 2 d^2 l2),
c[7] ->
k^2 (ax^2 + ay^2 - d^2 - 2 ax nxb + nxb^2 - 2 ay nyb + nyb^2),
c[8] -> (ax^2 + ay^2 - d^2 - 2 ax p0x + p0x^2 - 2 ay p0y + p0y^2),
c[9] -> 2 k ,
c[10] -> (ax^2 + ay^2 - d^2 + nxb p0x - ax (nxb + p0x) + nyb p0y -
ay (nyb + p0y))};
In[2]:= sols =
Solve[{c[1] + l1^2 c[2] + c[3] + l1 c[4] == 0,
c[5] l1^2 + l1 c[6] + c[7] + l2^2 c[8] + c[9] l2 c[10] == 0}, {l1,
l2}]
Out[2]= {{l2 -> (1/(
4 c[2]^2 c[
8]))(-2 c[2]^2 c[9] c[
10] - \[Sqrt](-8 c[
2]^2 (-2 c[1] c[2] c[5] - 2 c[2] c[3] c[5] + c[4]^2 c[5] +
c[4] Sqrt[-4 c[1] c[2] - 4 c[2] c[3] + c[4]^2] c[5] -
c[2] c[4] c[6] -
c[2] Sqrt[-4 c[1] c[2] - 4 c[2] c[3] + c[4]^2] c[6] +
2 c[2]^2 c[7]) c[8] + 4 c[2]^4 c[9]^2 c[10]^2)),
l1 -> (-c[4] - Sqrt[-4 c[1] c[2] - 4 c[2] c[3] + c[4]^2])/(
2 c[2])}, {l2 -> (1/(
4 c[2]^2 c[
8]))(-2 c[2]^2 c[9] c[
10] + \[Sqrt](-8 c[
2]^2 (-2 c[1] c[2] c[5] - 2 c[2] c[3] c[5] + c[4]^2 c[5] +
c[4] Sqrt[-4 c[1] c[2] - 4 c[2] c[3] + c[4]^2] c[5] -
c[2] c[4] c[6] -
c[2] Sqrt[-4 c[1] c[2] - 4 c[2] c[3] + c[4]^2] c[6] +
2 c[2]^2 c[7]) c[8] + 4 c[2]^4 c[9]^2 c[10]^2)),
l1 -> (-c[4] - Sqrt[-4 c[1] c[2] - 4 c[2] c[3] + c[4]^2])/(
2 c[2])}, {l2 -> (1/(
4 c[2]^2 c[
8]))(-2 c[2]^2 c[9] c[
10] - \[Sqrt](-8 c[
2]^2 (-2 c[1] c[2] c[5] - 2 c[2] c[3] c[5] + c[4]^2 c[5] -
c[4] Sqrt[-4 c[1] c[2] - 4 c[2] c[3] + c[4]^2] c[5] -
c[2] c[4] c[6] +
c[2] Sqrt[-4 c[1] c[2] - 4 c[2] c[3] + c[4]^2] c[6] +
2 c[2]^2 c[7]) c[8] + 4 c[2]^4 c[9]^2 c[10]^2)),
l1 -> (-c[4] + Sqrt[-4 c[1] c[2] - 4 c[2] c[3] + c[4]^2])/(
2 c[2])}, {l2 -> (1/(
4 c[2]^2 c[
8]))(-2 c[2]^2 c[9] c[
10] + \[Sqrt](-8 c[
2]^2 (-2 c[1] c[2] c[5] - 2 c[2] c[3] c[5] + c[4]^2 c[5] -
c[4] Sqrt[-4 c[1] c[2] - 4 c[2] c[3] + c[4]^2] c[5] -
c[2] c[4] c[6] +
c[2] Sqrt[-4 c[1] c[2] - 4 c[2] c[3] + c[4]^2] c[6] +
2 c[2]^2 c[7]) c[8] + 4 c[2]^4 c[9]^2 c[10]^2)),
l1 -> (-c[4] + Sqrt[-4 c[1] c[2] - 4 c[2] c[3] + c[4]^2])/(
2 c[2])}}
In[3]:= sols /. rules
Out[3]= {{l2 -> (-4 k (ax^2 + ay^2 - d^2 + nxb p0x - ax (nxb + p0x) +
nyb p0y - ay (nyb + p0y)) (ax^2 + ay^2 - 2 ax p0x + p0x^2 -
2 ay p0y + p0y^2 -
16 r^2)^2 - \[Sqrt](16 k^2 (ax^2 + ay^2 - d^2 + nxb p0x -
ax (nxb + p0x) + nyb p0y - ay (nyb + p0y))^2 (ax^2 +
ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 - 16 r^2)^4 -
8 (ax^2 + ay^2 - d^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2) (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 -
16 r^2)^2 (2 k^2 (ax^2 + ay^2 - d^2 - 2 ax nxb + nxb^2 -
2 ay nyb + nyb^2) (ax^2 + ay^2 - 2 ax p0x + p0x^2 -
2 ay p0y + p0y^2 - 16 r^2)^2 +
2 d^2 k^2 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 - 16 r^2) (nxb^2 + nyb^2 - 2 nxb p0x + p0x^2 -
2 nyb p0y + p0y^2 - 16 r^2) +
2 d^2 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 - 16 r^2) (32 k l2 r^2 -
16 l2^2 r^2) - (-2 d^2 k - 2 d^2 l2) (ax^2 + ay^2 -
2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
16 r^2) (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 - 16 r^2)) -
d^2 (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 -
16 r^2))^2 - (-2 d^2 k - 2 d^2 l2) (ax^2 + ay^2 -
2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
16 r^2) \[Sqrt](-4 k^2 (ax^2 + ay^2 - 2 ax p0x +
p0x^2 - 2 ay p0y + p0y^2 - 16 r^2) (nxb^2 +
nyb^2 - 2 nxb p0x + p0x^2 - 2 nyb p0y + p0y^2 -
16 r^2) -
4 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 - 16 r^2) (32 k l2 r^2 -
16 l2^2 r^2) + (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 - 16 r^2))^2) -
d^2 (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 -
16 r^2)) \[Sqrt](-4 k^2 (ax^2 + ay^2 - 2 ax p0x +
p0x^2 - 2 ay p0y + p0y^2 - 16 r^2) (nxb^2 +
nyb^2 - 2 nxb p0x + p0x^2 - 2 nyb p0y + p0y^2 -
16 r^2) -
4 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 - 16 r^2) (32 k l2 r^2 -
16 l2^2 r^2) + (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 -
16 r^2))^2))))/(4 (ax^2 + ay^2 - d^2 - 2 ax p0x +
p0x^2 - 2 ay p0y + p0y^2) (ax^2 + ay^2 - 2 ax p0x + p0x^2 -
2 ay p0y + p0y^2 - 16 r^2)^2),
l1 -> (32 l2 r^2 -
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 + ay (nyb - p0y) -
nyb p0y + p0y^2 -
16 r^2) - \[Sqrt](-4 k^2 (ax^2 + ay^2 - 2 ax p0x + p0x^2 -
2 ay p0y + p0y^2 - 16 r^2) (nxb^2 + nyb^2 - 2 nxb p0x +
p0x^2 - 2 nyb p0y + p0y^2 - 16 r^2) -
4 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
16 r^2) (32 k l2 r^2 - 16 l2^2 r^2) + (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 + ay (nyb - p0y) -
nyb p0y + p0y^2 - 16 r^2))^2))/(2 (ax^2 + ay^2 -
2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
16 r^2))}, {l2 -> (-4 k (ax^2 + ay^2 - d^2 + nxb p0x -
ax (nxb + p0x) + nyb p0y - ay (nyb + p0y)) (ax^2 + ay^2 -
2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
16 r^2)^2 + \[Sqrt](16 k^2 (ax^2 + ay^2 - d^2 + nxb p0x -
ax (nxb + p0x) + nyb p0y - ay (nyb + p0y))^2 (ax^2 +
ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 - 16 r^2)^4 -
8 (ax^2 + ay^2 - d^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2) (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 -
16 r^2)^2 (2 k^2 (ax^2 + ay^2 - d^2 - 2 ax nxb + nxb^2 -
2 ay nyb + nyb^2) (ax^2 + ay^2 - 2 ax p0x + p0x^2 -
2 ay p0y + p0y^2 - 16 r^2)^2 +
2 d^2 k^2 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 - 16 r^2) (nxb^2 + nyb^2 - 2 nxb p0x + p0x^2 -
2 nyb p0y + p0y^2 - 16 r^2) +
2 d^2 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 - 16 r^2) (32 k l2 r^2 -
16 l2^2 r^2) - (-2 d^2 k - 2 d^2 l2) (ax^2 + ay^2 -
2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
16 r^2) (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 - 16 r^2)) -
d^2 (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 -
16 r^2))^2 - (-2 d^2 k - 2 d^2 l2) (ax^2 + ay^2 -
2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
16 r^2) \[Sqrt](-4 k^2 (ax^2 + ay^2 - 2 ax p0x +
p0x^2 - 2 ay p0y + p0y^2 - 16 r^2) (nxb^2 +
nyb^2 - 2 nxb p0x + p0x^2 - 2 nyb p0y + p0y^2 -
16 r^2) -
4 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 - 16 r^2) (32 k l2 r^2 -
16 l2^2 r^2) + (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 - 16 r^2))^2) -
d^2 (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 -
16 r^2)) \[Sqrt](-4 k^2 (ax^2 + ay^2 - 2 ax p0x +
p0x^2 - 2 ay p0y + p0y^2 - 16 r^2) (nxb^2 +
nyb^2 - 2 nxb p0x + p0x^2 - 2 nyb p0y + p0y^2 -
16 r^2) -
4 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 - 16 r^2) (32 k l2 r^2 -
16 l2^2 r^2) + (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 -
16 r^2))^2))))/(4 (ax^2 + ay^2 - d^2 - 2 ax p0x +
p0x^2 - 2 ay p0y + p0y^2) (ax^2 + ay^2 - 2 ax p0x + p0x^2 -
2 ay p0y + p0y^2 - 16 r^2)^2),
l1 -> (32 l2 r^2 -
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 + ay (nyb - p0y) -
nyb p0y + p0y^2 -
16 r^2) - \[Sqrt](-4 k^2 (ax^2 + ay^2 - 2 ax p0x + p0x^2 -
2 ay p0y + p0y^2 - 16 r^2) (nxb^2 + nyb^2 - 2 nxb p0x +
p0x^2 - 2 nyb p0y + p0y^2 - 16 r^2) -
4 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
16 r^2) (32 k l2 r^2 - 16 l2^2 r^2) + (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 + ay (nyb - p0y) -
nyb p0y + p0y^2 - 16 r^2))^2))/(2 (ax^2 + ay^2 -
2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
16 r^2))}, {l2 -> (-4 k (ax^2 + ay^2 - d^2 + nxb p0x -
ax (nxb + p0x) + nyb p0y - ay (nyb + p0y)) (ax^2 + ay^2 -
2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
16 r^2)^2 - \[Sqrt](16 k^2 (ax^2 + ay^2 - d^2 + nxb p0x -
ax (nxb + p0x) + nyb p0y - ay (nyb + p0y))^2 (ax^2 +
ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 - 16 r^2)^4 -
8 (ax^2 + ay^2 - d^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2) (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 -
16 r^2)^2 (2 k^2 (ax^2 + ay^2 - d^2 - 2 ax nxb + nxb^2 -
2 ay nyb + nyb^2) (ax^2 + ay^2 - 2 ax p0x + p0x^2 -
2 ay p0y + p0y^2 - 16 r^2)^2 +
2 d^2 k^2 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 - 16 r^2) (nxb^2 + nyb^2 - 2 nxb p0x + p0x^2 -
2 nyb p0y + p0y^2 - 16 r^2) +
2 d^2 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 - 16 r^2) (32 k l2 r^2 -
16 l2^2 r^2) - (-2 d^2 k - 2 d^2 l2) (ax^2 + ay^2 -
2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
16 r^2) (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 - 16 r^2)) -
d^2 (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 -
16 r^2))^2 + (-2 d^2 k - 2 d^2 l2) (ax^2 + ay^2 -
2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
16 r^2) \[Sqrt](-4 k^2 (ax^2 + ay^2 - 2 ax p0x +
p0x^2 - 2 ay p0y + p0y^2 - 16 r^2) (nxb^2 +
nyb^2 - 2 nxb p0x + p0x^2 - 2 nyb p0y + p0y^2 -
16 r^2) -
4 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 - 16 r^2) (32 k l2 r^2 -
16 l2^2 r^2) + (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 - 16 r^2))^2) +
d^2 (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 -
16 r^2)) \[Sqrt](-4 k^2 (ax^2 + ay^2 - 2 ax p0x +
p0x^2 - 2 ay p0y + p0y^2 - 16 r^2) (nxb^2 +
nyb^2 - 2 nxb p0x + p0x^2 - 2 nyb p0y + p0y^2 -
16 r^2) -
4 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 - 16 r^2) (32 k l2 r^2 -
16 l2^2 r^2) + (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 -
16 r^2))^2))))/(4 (ax^2 + ay^2 - d^2 - 2 ax p0x +
p0x^2 - 2 ay p0y + p0y^2) (ax^2 + ay^2 - 2 ax p0x + p0x^2 -
2 ay p0y + p0y^2 - 16 r^2)^2),
l1 -> (32 l2 r^2 -
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 + ay (nyb - p0y) -
nyb p0y + p0y^2 -
16 r^2) + \[Sqrt](-4 k^2 (ax^2 + ay^2 - 2 ax p0x + p0x^2 -
2 ay p0y + p0y^2 - 16 r^2) (nxb^2 + nyb^2 - 2 nxb p0x +
p0x^2 - 2 nyb p0y + p0y^2 - 16 r^2) -
4 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
16 r^2) (32 k l2 r^2 - 16 l2^2 r^2) + (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 + ay (nyb - p0y) -
nyb p0y + p0y^2 - 16 r^2))^2))/(2 (ax^2 + ay^2 -
2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
16 r^2))}, {l2 -> (-4 k (ax^2 + ay^2 - d^2 + nxb p0x -
ax (nxb + p0x) + nyb p0y - ay (nyb + p0y)) (ax^2 + ay^2 -
2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
16 r^2)^2 + \[Sqrt](16 k^2 (ax^2 + ay^2 - d^2 + nxb p0x -
ax (nxb + p0x) + nyb p0y - ay (nyb + p0y))^2 (ax^2 +
ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 - 16 r^2)^4 -
8 (ax^2 + ay^2 - d^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2) (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 -
16 r^2)^2 (2 k^2 (ax^2 + ay^2 - d^2 - 2 ax nxb + nxb^2 -
2 ay nyb + nyb^2) (ax^2 + ay^2 - 2 ax p0x + p0x^2 -
2 ay p0y + p0y^2 - 16 r^2)^2 +
2 d^2 k^2 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 - 16 r^2) (nxb^2 + nyb^2 - 2 nxb p0x + p0x^2 -
2 nyb p0y + p0y^2 - 16 r^2) +
2 d^2 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 - 16 r^2) (32 k l2 r^2 -
16 l2^2 r^2) - (-2 d^2 k - 2 d^2 l2) (ax^2 + ay^2 -
2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
16 r^2) (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 - 16 r^2)) -
d^2 (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 -
16 r^2))^2 + (-2 d^2 k - 2 d^2 l2) (ax^2 + ay^2 -
2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
16 r^2) \[Sqrt](-4 k^2 (ax^2 + ay^2 - 2 ax p0x +
p0x^2 - 2 ay p0y + p0y^2 - 16 r^2) (nxb^2 +
nyb^2 - 2 nxb p0x + p0x^2 - 2 nyb p0y + p0y^2 -
16 r^2) -
4 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 - 16 r^2) (32 k l2 r^2 -
16 l2^2 r^2) + (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 - 16 r^2))^2) +
d^2 (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 -
16 r^2)) \[Sqrt](-4 k^2 (ax^2 + ay^2 - 2 ax p0x +
p0x^2 - 2 ay p0y + p0y^2 - 16 r^2) (nxb^2 +
nyb^2 - 2 nxb p0x + p0x^2 - 2 nyb p0y + p0y^2 -
16 r^2) -
4 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y +
p0y^2 - 16 r^2) (32 k l2 r^2 -
16 l2^2 r^2) + (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 +
ay (nyb - p0y) - nyb p0y + p0y^2 -
16 r^2))^2))))/(4 (ax^2 + ay^2 - d^2 - 2 ax p0x +
p0x^2 - 2 ay p0y + p0y^2) (ax^2 + ay^2 - 2 ax p0x + p0x^2 -
2 ay p0y + p0y^2 - 16 r^2)^2),
l1 -> (32 l2 r^2 -
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 + ay (nyb - p0y) -
nyb p0y + p0y^2 -
16 r^2) + \[Sqrt](-4 k^2 (ax^2 + ay^2 - 2 ax p0x + p0x^2 -
2 ay p0y + p0y^2 - 16 r^2) (nxb^2 + nyb^2 - 2 nxb p0x +
p0x^2 - 2 nyb p0y + p0y^2 - 16 r^2) -
4 (ax^2 + ay^2 - 2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 -
16 r^2) (32 k l2 r^2 - 16 l2^2 r^2) + (-32 l2 r^2 +
2 k (ax (nxb - p0x) - nxb p0x + p0x^2 + ay (nyb - p0y) -
nyb p0y + p0y^2 - 16 r^2))^2))/(2 (ax^2 + ay^2 -
2 ax p0x + p0x^2 - 2 ay p0y + p0y^2 - 16 r^2))}}
Regards,
--
Jean-Marc