matlab 函数

 

size(a,1)求矩阵的行数 size(a,2)求矩阵的列数，相当于length(a) size(a)同时求矩阵的行和列数

size(a,n)取矩阵a的第n维

 

示例一

>> a = [1 2 3; 4 5 6];

>> [m, n] = size(a)

m = 2， n = 3

示例二

>> a = [1 2 3; 4 5 6];

>> b = [4 5 6; 7 8 9];

>> d = zeros(2, 3, 2);

>> d(:, :, 1) = a;

>> d(:, :, 2) = b;

>> [m n p] = size(d)

m = 2， n = 3， p = 2

由此可见d是一个2×3×2的三维数组（这里我们也可以用reshape函数或者cat函数或者使用for循环来构建三维数组）。

>> [m n] = size(d)

m = 2，n = 6

这里m指出了第一维的长度， 而这里的n就等于剩下两维长度的乘积，即6。

>> m = size(d)

m = 2 3 2

示例三

>> [m n p q] = size(a)

m = 2， n = 3， p = 1， q = 1

转自360百科及其他参考

 

Resize image

Syntax

B = imresize(A, scale)
B = imresize(A, [mrows ncols])
[Y newmap] = imresize(X, map, scale)
[...] = imresize(..., method)
[...] = imresize(..., parameter, value,...)

Description

B = imresize(A, scale) returnsimage B that is scale timesthe size of A. The input image A canbe a grayscale, RGB, or binary image. If scale isbetween 0 and 1.0, B is smaller than A.If scale is greater than 1.0, B islarger than A.

B = imresize(A, [mrows ncols]) returnsimage B that has the number of rows and columnsspecified by [mrows ncols]. Either NUMROWS or NUMCOLS maybe NaN, in which case imresize computesthe number of rows or columns automatically to preserve the imageaspect ratio.

[Y newmap] = imresize(X, map, scale) resizesthe indexed image X. scale caneither be a numeric scale factor or a vector that specifies the sizeof the output image ([numrows numcols]). By default, imresize returnsa new, optimized colormap (newmap) with the resizedimage. To return a colormap that is the same as the original colormap,use the 'Colormap' parameter (see below).

[...] = imresize(..., method) resizesthe indexed image. method can be (1) atext string that specifies a general interpolation method, (2) a textstring that specifies an interpolation kernel, or (3) a two-elementcell array that specifies an interpolation kernel.