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waldy73
Dec6-04, 10:46 AM
This mathematica code works for version 4 but i can't get it to work in version 5. Does anybody have any sugestions.

F = {Fx, Fy, Fz};
r = {x[t], y[t], z[t]};
EF = {Ex, Ey, Ez};
BF = {Bx, By, Bz};
v = D[r, t]

F = q EF + q Cross[v, BF]

eq1 = F - m D[r, {t, 2}] == 0 // Thread;
eq1 // ColumnForm

initial = {
x[0] == 0, x'[0] == 0,
y[0] == 0, y'[0] == 0,
z[0] == 0, z'[0] == 0};

fields = Thread /@ {BF -> {0, 0, m ω0/
q}, EF -> {E0 Cos[ω t], 0, 0}} // Flatten

eqs = Join[eq1, initial] /. fields

dsol = DSolve[eqs, {x[t], y[t], z[t]}, t] // Flatten // FullSimplify
when i do this last part i get this message

DSolve::bvnul: "For some branches of the general solution, the given boundary \
conditions lead to an empty solution.

Thanks!

nbo10
Dec6-04, 10:53 AM
A better place to post this would be
http://groups-beta.google.com/group/comp.soft-sys.math.mathematica

They always come up with ingenious solutions.