help eye       

EYE Identity matrix.

    EYE(N) is the N-by-N identity matrix.

    EYE(M,N) or EYE([M,N]) is an M-by-N matrix with 1's on

    the diagonal and zeros elsewhere.

    EYE(SIZE(A)) is the same size as A.

See also ONES, ZEROS, RAND, RANDN.  

【例1.10.1-2】在指令窗中，运用lookfor找H1行（M函数文件的第一注释行）

lookfor fourier  

FFT Discrete Fourier transform.

FFT2 Two-dimensional discrete Fourier Transform.

FFTN N-dimensional discrete Fourier Transform.

IFFT Inverse discrete Fourier transform.