matlab mashgrid 函数

meshgrid 有三种语法,用来生成三维网格矩阵或二维网格矩阵

[X,Y] = meshgrid(x,y) ， x和y 都是一维数组，如x=[1：3]; y= [4：5]; 则生成的 X 和 Y 都是为 3X3 维的矩阵，

>> [X,Y] = meshgrid(1:3,4:5)

X =

     1     2     3
     1     2     3


Y =

     4     4     4
     5     5     5

[X,Y] = meshgrid(x)

>> [X,Y] = meshgrid(1:3)

X =

     1     2     3
     1     2     3
     1     2     3


Y =

     1     1     1
     2     2     2
     3     3     3

[X,Y,Z] = meshgrid(x,y,z)

>> [X,Y,Z] = meshgrid(1:3,4:5,6:8)

X(:,:,1) =

     1     2     3
     1     2     3


X(:,:,2) =

     1     2     3
     1     2     3


X(:,:,3) =

     1     2     3
     1     2     3


Y(:,:,1) =

     4     4     4
     5     5     5


Y(:,:,2) =

     4     4     4
     5     5     5


Y(:,:,3) =

     4     4     4
     5     5     5


Z(:,:,1) =

     6     6     6
     6     6     6


Z(:,:,2) =

     7     7     7
     7     7     7


Z(:,:,3) =

     8     8     8
     8     8     8

下边用一个例子来展示如何二维网格的结果图

[X,Y] = meshgrid(-2:.2:2, -2:.2:2);                                
Z = X .* exp(-X.^2 - Y.^2);                                        
surf(X,Y,Z)

meshgrid 和ndgrid的区别

[X,Y] = ndgrid(x,y)

>> [X,Y] = ndgrid(1:3,4:5)

X =

     1     1
     2     2
     3     3


Y =

     4     5
     4     5
     4     5

>> [Y,X] = ndgrid(4:5,1:3)

Y =

     4     4     4
     5     5     5


X =

     1     2     3
     1     2     3

从中我们可以看看出meshgrid 和 ndgrid 几乎是一样的，除了输入的X，Y的顺序要换一下 ，即 [Y,X] = ndgrid(y,x)和  [X,Y] = meshgrid(x,y)的结果是一样的。meshgrid更适合2-D或是3-D的 Cartesian space， 而ndgrid更适合多维的问题。