MATLAB复习资料

MATLAB复习资料

1、ones

Y = ones(n) returns an n-by-n matrix of 1s. An error message appears if n is not a scalar.

Y = ones(m,n) or Y = ones([m n]) returns an m-by-n matrix of ones.

Y = ones(d1,d2,d3...) or Y = ones([d1 d2 d3...]) returns an array of 1s with dimensions d1-by-d2-by-d3-by-....

Y = ones(size(A)) returns an array of 1s that is the same size as A.

Y =的（N）返回1，n×n矩阵。若N是不是一个标量出现一个错误消息。

Y =（M，N）的人（或y = [ M n ]）返回一个矩阵的M-和-n。

Y =的（D1，D2，D3……）或Y =（D1 D2 D3的[……]）返回1尺寸d1-by-d2-by-d3-by数组的…（Y =的大小（一））返回1，作为一个相同大小的数组

2、zeros

B = zeros(n) returns an n-by-n matrix of zeros. An error message appears if n is not a scalar.

B = zeros(m,n) or B = zeros([m n]) returns an m-by-n matrix of zeros.

B = zeros(d1,d2,d3...) or B = zeros([d1 d2 d3...]) returns an array of zeros with dimensions d1-by-d2-by-d3-by-... .

B = zeros(size(A)) returns an array the same size as A consisting of all zeros.

B = 0（N）返回零的n×n矩阵。如果n不是一个标量出现一个错误消息。

B（m，n）＝0或B = 0（[m n]）返回零点的M-和-n矩阵。

B = 0（D1，D2，D3……）或B = 0（D1 D2 D3 [……]）返回数组的尺寸d1-by-d2-by-d3-by零点—…。

B = 0（大小（一））返回一个数组组成的一个同样大小的所有零。

3、eye

Y = eye(n) returns the n-by-n identity matrix.

Y = eye(m,n) or eye([m n]) returns an m-by-n matrix with 1's on the diagonal and 0's elsewhere.

Y = eye(size(A)) returns an identity matrix the same size as A.

Y =眼（N）返回n-n矩阵。

Y =（M，N）眼或眼（[ M ]）收益率与1的对角线上的和0的其他地方的M-和-n矩阵。

Y =眼（大小（一））返回一个矩阵作为同样大小

4、ceil

B = ceil(A) rounds the elements of A to the nearest integers greater than or equal to A. For complex A, the imaginary and real parts are rounded independently.

B细胞（一）发一个元素到最近的整数大于或等于B.复杂，虚部和实部为圆形独立。

5、floor

B = floor(A) rounds the elements of A to the nearest integers less than or equal to A. For complex A, the imaginary and real parts are rounded independently.

Round

B =地板（一）发一个元素到最近的整数小于或等于B.复杂，虚部和实部为圆形独立。

圆形的

6、round

Y = round(X) rounds the elements of X to the nearest integers. For complex X, the imaginary and real parts are rounded independently.

Y =圆（x）轮x元素到最近的整数。对于复杂的X，虚部和实部为圆形独立。

7、fix

B = fix(A) rounds the elements of A toward zero, resulting in an array of integers. For complex A, the imaginary and real parts are rounded independently

. B =固定（一）轮朝零元素，导致一个整数数组。针对复杂，虚部和实部为圆形独立。

8、rot90

B = rot90(A) rotates matrix A counterclockwise by 90 degrees. B = rot90(A,k) rotates matrix A counterclockwise by k*90 degrees, where k is an integer.

B = rot90（一）矩阵的一个逆时针旋转90度。B = rot90（A，K）矩阵的逆时针旋转90度的k，其中k是整数。

9、fliplr

B = fliplr(A) returns A with columns flipped in the left-right direction, that is, about a vertical axis. If A is a row vector, then fliplr(A) returns a vector of the same length with the order of its elements reversed. If A is a column vector, then fliplr(A) simply returns A.

B = fliplr（）返回一个列将在左右方向，即，绕一垂直轴。如果是一个行向量，然后fliplr（一）返回一个向量，其元素的顺序相同长度的逆转。如果A是一个列向量，然后fliplr（一）只返回A。

10、flipup

B = flipud(A) returns A with rows flipped in the up-down direction, that is, about a horizontal axis. If A is a column vector, then flipud(A) returns a vector of the same length with the order of its elements reversed. If

A is a row vector, then flipud(A) simply returns A.

B = flipud（）返回一个行翻转在上下方向，那就是，关于水平轴。如果A是一个列向量，然后flipud （）返回一个向量，其元素的顺序相同长度的逆转。如果是一个行向量，然后flipud（一）只返回A。

11、Mean

M = mean(A) returns the mean values of the elements along different dimensions of an array.

If A is a vector, mean(A) returns the mean value of A.

If A is a matrix, mean(A) treats the columns of A as vectors, returning a row vector of mean values. If A is a multidimensional array, mean(A) treats the values along the first non-singleton dimension as vectors, returning an array of mean values.

M = mean(A,dim) returns the mean values for elements along the dimension of A specified by scalar dim.

M =平均（）返回一个数组尺寸沿不同元素的平均值。

如果是一个向量，意味着（）返回A的平均值。

如果是一个矩阵，意味着（一）以作为载体的列的平均值，返回一个行向量。如果是一个多维数组，意味着（一）治疗对第一个非单维向量，返回的平均值的数组。

M =平均（一，DIM）返回沿着一个由标量DIM指定的维度元素的平均值。

12、median

M = median(A) returns the median values of the elements along different dimensions of an array. If A is a vector, median(A) returns the median value of A. If A is a matrix, median(A) treats the columns of A as vectors, returning a row vector of median values.

If A is a multidimensional array, median(A) treats the values along the first nonsingleton dimension as vectors, returning an array of median values.

M = median(A,dim) returns the median values for elements along the dimension of A specified by scalar dim.

M =中位数（）返回的数组的尺寸沿不同的元素值的中位数。如果是一个向量，中值（一）如果是一个矩阵返回A的中位数，中位数（一）把一个向量列中值，返回一个行向量。

如果是一个多维数组，中值（一）治疗对第一个nonsingleton尺寸为载体，返回数组的中位数。

M =中位数（一，DIM）返回沿着一个由标量DIM指定的维度元素平均值。

13、max

C = max(A) returns the largest elements along different dimensions of an array.

If A is a vector, max(A) returns the largest element in A. If A is a matrix, max(A) treats the columns of A as vectors, returning a row vector containing the maximum element from each column.

If A is a multidimensional array, max(A) treats the values along the first non-singleton dimension as vectors, returning the maximum value of each vector.

C = max(A,B) returns an array the same size as A and B with the largest elements taken from A or B.

C = max(A,[],dim) returns the largest elements along the dimension of A specified by scalar dim. For example, max(A,[],1) produces the maximum values along the first dimension (the rows) of A.

[C,I] = max(...) finds the indices of the maximum values of A, and returns them in output vector I. If there are several identical maximum values, the index of the first one found is returned.

C = max（）返回的数组不同尺寸最大的元素。

如果是一个向量，max（a）如果是一个矩阵，返回的最大元素的最大值（一），以作为载体的列，还含有每一列的最大元素的行向量。

如果是一个多维数组，max（a）治疗对第一个非单维度为载体，返回每个向量的最大值。

C = max（a，b）返回一个数组作为A和B的最大元素取自或b的大小一样。

C = max（a，[ ]，返回一个昏暗的）的标量DIM指定尺寸最大的元素。例如，max（a，[ ]，1）产生的最大值沿第一维（行）A.

[ C ]，我= max（……）找到一个最大值的指标，并返回他们在输出向量，如果有几个相同的最大值，则返回第一个找到的指标。

14、min

C = min(A) returns the smallest elements along different dimensions of an array.

If A is a vector, min(A) returns the smallest element in A.

If A is a matrix, min(A) treats the columns of A as vectors, returning a row vector containing the minimum element from each column.

If A is a multidimensional array, min operates along the first nonsingleton dimension.

C = min(A,B) returns an array the same size as A and B with the smallest elements taken from A or B.

C = min(A,[],dim) returns the smallest elements along the dimension of A specified by scalar dim. For example, min(A,[],1) produces the minimum values along the first dimension (the rows) of A.

[C,I] = min(...) finds the indices of the minimum values of A, and returns them in output vector I. If there are several identical minimum values, the index of the first one found is returned.

C＝min（）返回的数组不同尺寸最小的元素。

如果是一个向量，min（）返回最小的元素，A.

如果是一个矩阵，min（一）以作为载体的列，还包含了每一列的最小元素的行向量。

如果是一个多维数组，闵沿着第一UL尺寸。

C＝min（A，B）返回一个数组作为和B的最小元素取自或b的大小一样。

C＝min（一，[ ]，返回一个昏暗的）的标量DIM指定尺寸最小的元素。例如，MIN（一，[ ]，1）产生的最小值沿第一维（行）A.

[ C ]，我= min（……）找到一个最小值的指标，并将它们输出向量如果有几个相同的最小值，则返回第一个找到的指标。

15、ans

MATLAB creates the ans variable automatically when you specify no output argument.

MATLAB创建了ANS变量自动当你没有指定输出参数。

16NaN

NaN returns the IEEE arithmetic representation for Not-a-Number (NaN). These result from operations which have undefined numerical results.

南返回非数字的算术表示（南）。这些结果从数值结果未定义操作。

17InF

Inf returns the IEEE arithmetic representation for positive infinity. Infinity results from operations like division by zero and overflow, which lead to results too large to represent as conventional floating-point values.

INF返回正无穷大的IEEE算术表示。无限的结果来自行动像被零除和溢出，导致的结果太大代表传统的浮点值。

直方图

function [im_hist] = im_histogram(im)

[m n]=size(im);

im_hist=zeros(1,256);

for k=1:m

for p=1:n

im_hist(im(k,p)+1)=im_hist(im(k,p)+1)+1;

end

end

plot(im_hist)

字符定位

bw = imread('text.png');

a = bw(32:45,88:98);

imshow(bw);

figure, imshow(a);

C = filter2(a,bw)

%C = real(ifft2(fft2(bw) .* fft2(rot90(a,2),256,256)));

thresh = 66; % Use a threshold that's a little less than max.

figure, imshow(C > thresh)% Display showing pixels over threshold.

中值滤波

function [im_filtered]=median_filter(im)

[m,n]=size(im);

for k = 2:m-1

for j = 2:n-1

temp = im(k-1:k+1,j-1:j+1);

temp = reshape(temp,1,9);

for i = 1:9

for t = i+1:9

if temp(t) > temp(i)

temp1 = temp(t);

temp(t) = temp(i);

temp(i) = temp1;

end

end

end

im_filtered(k,j) = temp(5);

end

end

%imwrite(binary_im,'e:\temp\output.bmp','bmp');

梯度

[x,y]=meshgrid(-2:0.05:2,-2:0.05:2);

z=x.*exp(-x.^2-y.^2);

[px,py]=gradient(z,0.05,0.05);

td=sqrt(px.^2+py.^2);

subplot(221);

imagesc(z);

subplot(222);

imagesc(td);

colormap('gray')

平移和周期延拓

N=24;M=8;m=3

n=0:N-1;

x1=(0.8).^n;

x2=[(n>=0)&(n

x=x1.*x2;

xm=zeros(1,N);

for k=m+1:m+M

xm(k)=x(k-m);

end

xc=x(mod(n,M)+1);

subplot(311);stem(n,x,'.');ylabel('x(n)');

subplot(312);stem(n,xm,'.');ylabel('x(n-3)'); subplot(313);stem(n,xc,'.');ylabel('x((n))-8');