Basically I am trying to recreate this Robert M. Dickau - Magnetic Pendulum
now my differential equation is
NDSolve[{x''[t] + Rx'[t] - Sum from i=1to3 of (x-x[t])/(rootof(x-x[t])^2 +[y-y[t])^2 +d^2)^3 + Qx[t]==0,
{y''[t] + Ry'[t] - Sum from i=1to3 of (y-y[t])/(rootof(x-x[t])^2 +[y-y[t])^2 +d^2)^3 + Qy[t]==0, x[0]==-.95, y[0]==0.09, x'[0]==0, y'[0]==0}, {x,y}, {t,0,100}, MaxSteps -> 1000]
I have assigned values to R Q and d, and please note than the x's and y's which are not of t, should be subscript i.
I get the error,
"The first argument must have both an equation and an initial condition."
I keep compare my equation to other example equations but I can't see whats wrong.
Any anyone shed any light?
Very much appreciated.