Matab空值补全NaN

% U2(1:301,2144:2242)=NaN;空值补全NaN

 

Inf  ====无穷大infinite的英文前三个字母，

无穷大量+∞，同样地，-∞可以表示为-Inf。在MATLAB程序执行时，即使遇到了以0为除数的运算，也不会终止程序的运行，而只给出一个“除0”警告，并将结果赋成Inf，继续执行

实际意思是当算出的结果大于某个数（这个数很大，比如10的很多次方），则MATLAB认为就是无穷大了，并返回 inf。

>> help clf
 CLF Clear current figure.
    CLF deletes all children of the current figure with visible handles.
 
    CLF RESET deletes all children (including ones with hidden
    handles) and also resets all figure properties, except Position
    and Units, to their default values.
 
    CLF(FIG) or CLF(FIG,'RESET') clears the single figure with handle FIG.
 
    See also cla, reset, hold.

    Reference page in Help browser
       doc clf

 

Y = diff(X) calculates differences between adjacent elements of X.

If X is a vector, then diff(X) returns a vector, one element shorter than X, of differences between adjacent elements: [X(2)-X(1) X(3)-X(2) ... X(n)-X(n-1)]
If X is a matrix, then diff(X) returns a matrix of row differences: [X(2:m,:)-X(1:m-1,:)]
In general, diff(X) returns the differences calculated along the first non-singleton (size(X,dim) > 1) dimension of X. Y = diff(X,n) applies diff recursively n times, resulting in the nth difference. Thus, diff(X,2) is the same as diff(diff(X)). Y = diff(X,n,dim) is the nth difference function calculated along the dimension specified by scalar dim. If order n equals or exceeds the length of dimension dim, diff returns an empty array