Matlab R2007a 没有了smooth命令？

mapi

help smooth了一下，找不到了。不知道这样的命令是什么？
我要解决的问题是：试验测到 y=f(x) 曲线，不光滑，有峰值，但理论上是光滑的。所以想过滤，或者平滑曲线。

feynmand

是不是你用的matlab安装有问题？这个命令应该一直在的。我用2008a试了一下有的阿，另外看了release notes 没有说smooth命令有过改变。

help smooth
SMOOTH  Smooth data.
    Z = SMOOTH(Y) smooths data Y using a 5-point moving average.

    Z = SMOOTH(Y,SPAN) smooths data Y using SPAN as the number of points used
    to compute each element of Z.

    Z = SMOOTH(Y,SPAN,METHOD) smooths data Y with specified METHOD. The
    available methods are:

            'moving'   - Moving average (default)
            'lowess'   - Lowess (linear fit)
            'loess'    - Loess (quadratic fit)
            'sgolay'   - Savitzky-Golay
            'rlowess'  - Robust Lowess (linear fit)
            'rloess'   - Robust Loess (quadratic fit)

    Z = SMOOTH(Y,METHOD) uses the default SPAN 5.

    Z = SMOOTH(Y,SPAN,'sgolay',DEGREE) and Z = SMOOTH(Y,'sgolay',DEGREE)
    additionally specify the degree of the polynomial to be used in the
    Savitzky-Golay method. The default DEGREE is 2. DEGREE must be smaller
    than SPAN.

    Z = SMOOTH(X,Y,...) additionally specifies the X coordinates.  If X is
    not provided, methods that require X coordinates assume X = 1:N, where
    N is the length of Y.

    Notes:
    1. When X is given and X is not uniformly distributed, the default method
    is 'lowess'.  The 'moving' method is not recommended.

    2. For the 'moving' and 'sgolay' methods, SPAN must be odd.
    If an even SPAN is specified, it is reduced by 1.

    3. If SPAN is greater than the length of Y, it is reduced to the
    length of Y.

    4. In the case of (robust) lowess and (robust) loess, it is also
    possible to specify the SPAN as a percentage of the total number
    of data points. When SPAN is less than or equal to 1, it is
    treated as a percentage.

    For example:

    Z = SMOOTH(Y) uses the moving average method with span 5 and
    X=1:length(Y).

    Z = SMOOTH(Y,7) uses the moving average method with span 7 and
    X=1:length(Y).

    Z = SMOOTH(Y,'sgolay') uses the Savitzky-Golay method with DEGREE=2,
    SPAN = 5, X = 1:length(Y).

    Z = SMOOTH(X,Y,'lowess') uses the lowess method with SPAN=5.

    Z = SMOOTH(X,Y,SPAN,'rloess') uses the robust loess method.

    Z = SMOOTH(X,Y) where X is unevenly distributed uses the
    'lowess' method with span 5.

    Z = SMOOTH(X,Y,8,'sgolay') uses the Savitzky-Golay method with
    span 7 (8 is reduced by 1 to make it odd).

    Z = SMOOTH(X,Y,0.3,'loess') uses the loess method where span is
    30% of the data, i.e. span = ceil(0.3*length(Y)).

    See also spline.

    Reference page in Help browser
       doc smooth

mapi

谢谢!
不过我记得安装好像没有问题。我再看看。

lyares

如果只是想平滑曲线，也可以用filter函数

You can use filter to find a running average without using a for loop. This example finds the running average of a 16-element vector, using a window size of 5.

data = [1:0.2:4]';
windowSize = 5;
filter(ones(1,windowSize)/windowSize,1,data)

其实smooth内部就是用filter来实现的