Reputation: 55
I'm trying to solve this equation for x (or y). Is there some way to do it in Matlab? The "simplify" function (even with "steps",100,"All", true) doesn't do it.
-k+Sqrt[x^2+y^2]+Sqrt[(x-ax)^2+y^2]+Sqrt[(x-bx)^2+(y-by)^2]
Upvotes: 1
Views: 48
Reputation: 17638
A symbolic solution does not exist in the general case, because the problem amounts to solving an 8th degree algebraic equation.
Defining the points M(x,y)
, O(0,0)
, A(ax,0)
and B(bx,by)
in the plane, the equation can be written as MO + MA + MB = k
. The solution set M
is the locus of points with constant sum of distances to 3 fixed points. This is called a 3-ellipse which is a curve of algebraic degree 2^3 = 8
in the general case.
If F
is the Fermat point of triangle OAB
and f = FO + FA + FB
, then no solutions exist for k < f
. More material and links related to 3-ellipses can be found on this multiellipse page.
Upvotes: 1