Matlab里四个函数：Floor, Ceil, Fix, Round

转自：http://blog.mcuol.com/User/nielixian/Article/7946_1.htm

floor：朝负无穷方向舍入

B = floor(A) rounds the elements of A to the nearest integers less than or equal to A.

ceil：朝正无穷方向舍入

B = ceil(A) rounds the elements of A to the nearest integers greater than or equal to A.

fix：朝零方向舍入

B = fix(A) rounds the elements of A toward zero, resulting in an array of integers.

round：四舍五入

B = round(A) rounds the elements of X to the nearest integers.  

norm：求矩阵或向量的泛数

             x = [1 2 3 4 5 6];

             norm(x) = 9.5394

Example：

a=         [-0.9,    -2.1,    -0.4,    0.3,    0.8,    1.1,    2.7,    -1.2+2.9i];

floor(a)=[ -1,      -3,      -1,      0,      0,      1,      2,       -2+2i]

ceil(a)= [ 0,       -2,       0,      1,      1,      2,      3,       -1+3i]

fix(a)=    [ 0,       -2,       0,      0,      0,      1,      2,       -1+2i]

round(a)=[-1,       -2,       0,      0,      1,      1,      3,       -1+3i]

注：For complex X, for all the four fuctions the imaginary and real parts are rounded independently.