ERA 模态识别(Era.m)

代码说明：

%% input% h: Impulse response% n: Degree of freedoms(Only if structural system)% r: number of rows% s: number of columns%% output% A: State Matrix, 2n*2n. n is DOFs, 2*n is the number of state variables% B: Input Matrix, 2n*p. p is the number of input% G: Output Matrix, q*2n. q is the number of output