A collection of simple functions in MATLAB?

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Too much. Look at it with help.

And it should be looked at in a classified way.

The function given by the subject is a piecewise function, which can be implemented with ** in MATLAB

1. First of all, create a custom segmentation function, PieceWise fun(x), and save it as a PieceWise file. Piecewise fun(x) function, for

function y=piecewise_fun(x)

n=length(x);

for i=1:n

if x(i)>=0 & x(i)<=1

y(i)=x(i);

elseif x(i)>1 & x(i)<=2

y(i)=2*x(i)-1;

elseif x(i)>2

y(i)=x(i).^2-1;

else

y(i)=0;

end

end

end

2. Then in the command window of MATLAB, execute the next command

>>x=-10：：10;% for example

>>y=piecewise_fun(x)

>>plot(x,y),grid on

>>xlabel('x'),ylabel('y(x)')

1. Beginner - learn the relevant operations of mathematics (matrix) and the application of various common functions.

2. Re-introduction - learn the programming methods and skills of MATLAB object-oriented language.

3. A glimpse of the door - because MATLAB is just a tool software, the so-called fool's language, so it is just an auxiliary thing, not to learn MATLAB for the sake of learning MATLAB, the most important thing for us is to let him serve us, should be based on their specific application field at this stage or in the future, MATLAB provides a lot of toolboxes (signal processing, control, voice, etc.), position yourself, and get twice the result with half the effort.

4. Explore by yourself - MATLAB is not like C language, it is very scattered, you should write down the functions used in your work and study, and move towards the master.

Take a look at the basic grammar and improve it in practice, and when you have time, you can read the classic textbooks to be proficient. It would also be helpful to find more classic programs and look into them.

1) Divide sub-areas.

Method 1: Image I is a matrix, and dividing it into sub-regions is to take the corresponding rows and columns of the matrix according to a certain law.

For example, in an i 100*100 matrix, the 10*10 sub-regions are:

Then the first block is: (1:10,1:10) The sub-region number is (1,1).

The second block is: (11:20,10) The sub-area is numbered (2,1).

And so on: this can be achieved by looping:

for i=1:10;

for j=1:10;

eval(['i' num2str(i) num2str(j) 'i(1+10*(i-1):10+10*(i-1),1+10*(j-1):10+10*(j-1))'

endend

Each sub-region is i11, i12, i13....i1010

Example: <>

Method 2: Use the Crop command to crop out the corresponding area

i2=imcrop（i,rect）

The rect is the boundary of the corresponding area.

For example: i11=imcrop(i,[1,1,10,10]); That is, the coordinates of the upper-left and lower-right corners of the subregion.

An example is as follows:

for i=1:10;

for j=1:10;

eval(['i' num2str(i) num2str(j) 'imcrop(i,[1+10*(i-1),1+10*(i-1),10+10*(j-1),10+10*(j-1)])

endend

<>2) How to find and draw a histogram:

x,n]=hist(i(:)1:255);

x returns the midpoint between cells of the abscissa array --- frequency statistics.

n returns the frequency of each interval --- ordinate array.

plot(n,x)

In addition, it can also be used directly:

p=imhist(i);

plot(p);

Probability density: plot(p n);

n is the total number of points in the region, for example, 10*10.

3) Use the division area with the grayscale histogram:

for i=1:10;

for j=1:10;

p(10*(i-1)+j,:)imhist(i(1+10*(i-1):10+10*(i-1),1+10*(j-1):10+10*(j-1)))

endend

Then the histogram statistics for each subregion are in each row of the p-matrix, for a total of 100 rows.