invariants不变序列invariantadj.不变的n.不变量invariant measure problem不变测度问题invariant linear subspace不变线性子空间invariant of straintensor应变张量不变量invariant pseudo-metric不变伪度量invariant in space-time时空不变式invariant subspace method不变子空间方法invariant random variable不变随机变量invariant operator method不变量方法invariant embedding method不变量嵌入法invariant moments matching不变矩匹配