关于Matlab里面的四个取整（舍入）函数：Floor, Ceil, Fix, Round的解释(转)

转自http://blog.sina.com.cn/s/blog_48ebd4fb010009c2.html

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.

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.