版主说的有理,不过可能有误导
实际上可以使用 value 函数来得到含有惰性函数的计算结果,
举例如下
Diff(sin(x), x$n);
value(Diff(sin(x),`$`(x,n)));
Note that in the context of a call to diff (or Diff), n entering diff(f(x),[`$`(x,n)]) is understood to be an integer; that is: diff computes integer order derivatives. To compute fractional derivatives see fracdiff
值得注意的是
diff 默认 n 为整数
分数阶导数, 使用 fracdiff