然后计算v就提示内存不足了，求助该怎么办/(ㄒoㄒ)/~~
代码：
Subscript[G, 4] = \!\(
\*UnderoverscriptBox[\(\[Sum]\), \(i = 0\), \(9\)]\(
\*UnderoverscriptBox[\(\[Sum]\), \(j = 0\), \(i\)]
\*SubscriptBox[\(a\), \(
\*UnderoverscriptBox[\(\[Sum]\), \(p = 0\), \(i\)]p + j\)]*
\*SuperscriptBox[\(x\), \(2*j\)]*
\*SuperscriptBox[\(t\), \(2*i - 2*j\)]\)\);
Subscript[H, 4] = \!\(
\*UnderoverscriptBox[\(\[Sum]\), \(i = 0\), \(9\)]\(
\*UnderoverscriptBox[\(\[Sum]\), \(j = 0\), \(i\)]
\*SubscriptBox[\(b\), \(
\*UnderoverscriptBox[\(\[Sum]\), \(p = 0\), \(i\)]p + j\)]*
\*SuperscriptBox[\(x\), \(2*j\)]*
\*SuperscriptBox[\(t\), \(2*i - 2*j\)]\)\);
Subscript[F, 4] = \!\(
\*UnderoverscriptBox[\(\[Sum]\), \(i = 0\), \(10\)]\(
\*UnderoverscriptBox[\(\[Sum]\), \(j = 0\), \(i\)]
\*SubscriptBox[\(c\), \(
\*UnderoverscriptBox[\(\[Sum]\), \(p = 0\), \(i\)]p + j\)]*
\*SuperscriptBox[\(x\), \(2*j\)]*
\*SuperscriptBox[\(t\), \(2*i - 2*j\)]\)\);
Subscript[u,
4] = (1 + (Subscript[G, 4] + I*t*Subscript[H, 4])/Subscript[F, 4])*
E^(I*t);
v = Simplify[
ComplexExpand[(I*D[Subscript[u, 4], t] +
1/2*D[Subscript[u, 4], {x, 2}] + (Abs[Subscript[u, 4]])^2*
Subscript[u, 4])*(Subscript[F, 4])^3/E^(I*t)]]

似乎从来没有见过相关的讨论……考虑到硬盘的读写速度，我个人对此也并不期待。还是改变算法，避免强度过高的符号计算比较现实一些；换台内存大点的电脑可能也是个办法。