Matlab

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Today, the editor brings you matlab two-dimensional drawing

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#1 本期主题介绍

The topic of this issue

如果您了解过Matlab，

您肯定知道Matlab不只是计算！

Matlab还有一个强大的绘图功能！

本期话题将对matlab的二维图进行介绍。

请感兴趣的朋友和小编开启

学习Matlab的二维绘图之旅吧！

If you know Matlab,

You must know that Matlab is more than just computing!

Matlab also has a powerful drawing function!

The topic of this issue will introduce the two-dimensional map of matlab.

Please open it with interested friends and editors

Learn the journey of two-dimensional drawing in Matlab!

#2 Matlab二维绘图

Matlab two-dimensional drawing

1.绘制二维曲线

Draw a two-dimensional curve

plot函数的基本调用格式为：plot(x,y)

其中x和y为长度相同的向量，分别用于存储x坐标和y坐标数据；当x是实向量时，plot(x)以该向量元素的下标为横坐标，元素值为纵坐标画出一条折线图，当x为矩阵时，plot(x)以列为向量画出几条折线（矩阵列数）；当x,y是同维矩阵时，则以x,y对应列元素为横、纵坐标分别绘制曲线，曲线条数等于矩阵的列数。

The basic calling format of the plot function is: plot(x,y)

Where x and y are vectors of the same length, which are used to store x coordinate and y coordinate data respectively; when x is a real vector, plot(x) uses the subscript of the vector element as the abscissa, and the element value is the ordinate to draw A polyline graph, when x is a matrix, plot(x) draws several polylines (the number of matrix columns) with columns as vectors; when x and y are matrixes of the same dimension, the corresponding column elements of x and y are horizontal and Draw curves on the ordinate, and the number of curves is equal to the number of columns in the matrix

#3 Matlab 二维绘图实际操作

Matlab two-dimensional drawing actual operation

1.plot绘单条曲线图

plot draw a single curve graph

x=0:0.01*pi:2*pi;

y=sin(x);

plot(x,y)

2.plot绘制多条曲线图

plot plots multiple curves

格式为：plot(x,y1,x2,y2,......,xn,yn)

The format is: plot(x,y1,x2,y2,......,xn,yn)

以向量对的形式绘制曲线。

Draw curves in the form of vector pairs.

x=0:0.01*pi:2*pi;

y1=sin(x);

y2=sin(x-0.25*pi);

y3=sin(x-0.5*pi);

plot(x,y1,x,y2,x,y3)

plot(x,y1,'-.b',x,y2,'--r',x,y3,'-.gh')

%b代表的是蓝色，r为红色，gh为绿色

%b represents blue, r is red, gh is green

3.hold on 与 hold off的应用

Application of hold on and hold off

如果绘制一个曲线后，想要保持当前曲线不变，在当前曲线基础上绘制新的曲线，这时我们可以采用”hold on”，关闭时可以用”hold off"。

If you want to keep the current curve unchanged after drawing a curve, and draw a new curve based on the current curve, we can use "hold on" at this time, and use "hold off" when closing.

x=0:0.1:1;

y=x;

plot(x,y)

hold on

x=1:0.1:2;

y=0.5*x.^4+0.5;

plot(x,y)

hold on

x=2:0.1:5;

y=-x.^2+9*x-5.5;

plot(x,y)

hold off

4.绘制特殊的二维曲线，比如只想要描述点，而不想要线

Draw a special two-dimensional curve, such as only wanting to describe points, but not lines

x=0:pi/15:4*pi;

y=exp(2*cos(x));

plot(x,y,'r+')

5.绘制对数曲线

Draw a logarithmic curve

x=linspace(1,100,100);

y=exp(x);

loglog(x,y)

%这样就绘制了双对数曲线

%This draws a double logarithmic curve

x=linspace(1,100,100);

y=exp(x);

semilogy(x,y)

%Y为对数坐标轴

%Y is the logarithmic axis

x=linspace(1,100,100);

y=exp(x);

semilogx(x,y)

%x为对数坐标轴

%x is the logarithmic axis

6.fplot函数的应用

%flot函数的基本用法：fplot(f,lims,参数）

f代表一个函数，通常采用函数句柄的形式。lims为x轴的取值范围，默认值为[-5，5]。参数与plot函数相同。

Application of fplot function

The basic usage of %flot function: fplot(f, lims, parameter)

f represents a function, usually in the form of a function handle. lims is the value range of the x-axis, and the default value is [-5, 5]. The parameters are the same as the plot function.

xt = @(t) cos(3*t);

yt = @(t) sin(2*t);

fplot(xt,yt)

%fplot双输入函数的基本用法：fplot(funx,funy,tlims,参数)

funx、funy代表函数，通常采用函数句柄的形式，tlims为参数函数funx和funy得到自变量取值范围。

fplot(@(t) t.*sin(t), @(t) t.*cos(t))

The basic usage of %fplot dual input function: fplot(funx, funy, tlims, parameter)

funx and funy represent functions, usually in the form of a function handle, tlims is the parameter function funx and funy to get the value range of the independent variable.

fplot(@(t) t.*sin(t), @(t) t.*cos(t))

7.polarplot函数的应用

Application of .polarplot function

t=0:0.1*pi:4*pi;

a=abs(sin(2*t).*cos(2*t));

polarplot(t,a,'-b+')

8.绘制图形的辅助操作

%给图形添加标注

%title (图形标题）

title('图形标题','Color,'r','FontSize',24)

%xlable(x轴说明）

%ylable（y轴说明）

%text(x,y,图形说明）

%legend(图例)

x=linspace(0,2*pi,100);

y1=sin(x);

y2=sin(2*x);

plot(x,sin(x),x,sin(2*x))

legend('sin(x)','sin(3x)','sin(2x)')

9.坐标轴

Coordinate axis control控制

%axis[xmin,xmax,ymin,ymax,zmin,zmax]

%axis equal:纵横坐标轴次采用等长刻度

%axis square:产生正方形坐标系（默认为矩形）

%axis auto:使用默认设置

%axis off:不显示坐标轴

%axis on :显示坐标轴

%给坐标轴加网格

%grid on

%grid off

%grid

%给坐标系加边框

%box on

%bix off

%box

%图形保存

%hold on

%hold off

%hold

x=linspace(0,2*pi,100);

t=linspace(0,2*pi,100);

x=sin(t);

y=cos(t);

plot(x,y,'b')

hold on;

plot(2*x,2*y,'r+');

grid on

axis([-2.2,2.2,-2.2,2.2])

axis equal

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参考资料：Google翻译、哔哩哔哩

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