9楼: Originally posted by xzczd at 2015-10-14 10:52:53
……因为Plot是用来画实数域的图像的，而你的方程里都含了虚数单位了，十有八九都是（事实上也确实是）在复数域上啊。...

NDSolve[{I x'[t] == 3/10 x[t] - 4/10 Exp[I t/2] y[t],
  I y'[t] == -4/10 Exp[-I t/2] x[t] - 3/10 y[t], x@0 == 0, y@0 == 1}, {x, y}, {t, 0, 10}]
Plot[Abs[{x[t], y[t]}] /. nsol // Evaluate, {t, 0, 10}]

eqn = {I x'[t] == 3/10 x[t] - 4/10 Exp[I t/2] y[t],
   I y'[t] == -4/10 Exp[-I t/2] x[t] - 3/10 y[t], x@0 == 0, y@0 == 1};
representWithy = Solve[eqn[[2]], x[t]][[1, 1, -1]];
eqn[[{1, 3, 4}]] /. x -> (Function[t, #] &@representWithy)
ysol = DSolve[{%, eqn[[-1]]}, y, t];
(*y[t]=*)y[t] /. ysol
(*x[t]=*)representWithy /. ysol

2楼: Originally posted by xzczd at 2015-10-14 09:50:32
NDSolve会没反应八成是你语法错了。试试这个：

NDSolve
Plot[Abs /. nsol // Evaluate, {t, 0, 10}]



至于DSolve，截止10.2版，Mathematica的DSolve是有许多不尽如人意的地方的。（不过即将推出的10.3版似 ...

2楼: Originally posted by xzczd at 2015-10-14 09:50:32
NDSolve会没反应八成是你语法错了。试试这个：

NDSolve
Plot[Abs /. nsol // Evaluate, {t, 0, 10}]



至于DSolve，截止10.2版，Mathematica的DSolve是有许多不尽如人意的地方的。（不过即将推出的10.3版似 ...