1、length函数：计算向量或矩阵的长度

2、用法说明

      y = length(x) 函数计算指定向量或矩阵的长度y。如果参数变量x是向量，则返回其长度；如果参数变量是非空矩阵，则length(x)与max(size(x))等价

3、举例说明

>> x = \'youhaidong\'

x =

youhaidong

>> y = length(x)

y =

    10

>> x = rand(6,6)

x =

    0.8147    0.2785    0.9572    0.7922    0.6787    0.7060
    0.9058    0.5469    0.4854    0.9595    0.7577    0.0318
    0.1270    0.9575    0.8003    0.6557    0.7431    0.2769
    0.9134    0.9649    0.1419    0.0357    0.3922    0.0462
    0.6324    0.1576    0.4218    0.8491    0.6555    0.0971
    0.0975    0.9706    0.9157    0.9340    0.1712    0.8235

>> y = length(x)

y =

     6

4、附录

>> help length
 length   Length of vector.
    length(X) returns the length of vector X.  It is equivalent
    to MAX(SIZE(X)) for non-empty arrays and 0 for empty ones.
   
    See also numel.

    Overloaded methods:
       timer/length
       serial/length
       daqdevice/length
       daqchild/length
       distributed/length
       codistributed/length
       Composite/length
       gpuArray/length
       fints/length
       videosource/length
       videoinput/length
       visa/length
       udp/length
       tcpip/length
       icgroup/length
       icdevice/length
       i2c/length
       gpib/length
       Bluetooth/length
       xregpointer/length
       mbcstore/length
       guidarray/length
       cgrules/length
       designdev/length
       des_constraints/length
       coninputfactor/length
       xregcontainer/length
       xregmulti/length
       xregcovariance/length
       xregmonitorplotproperties/length
       xregdataset/length
       cgtradeoffkeytable/length
       dataset/length
       categorical/length
       tscollection/length

    Reference page in Help browser
       doc length