# matlab学习2-画线

## 1.1plot（x,y,线性）

``````x=linspace(0,2*pi,30);
plot(x,sin(x),'r',x,cos(x),'-')``````

## 1.2符号函数画图ezplot('f(x)',[a,b])

1、在【0，pi】上画y=sin(x)

``ezplot('sin(x)',[0,pi])``

2、在【0，2pi】画cos(t)^3,sin(t)^3,星图

`` ezplot('cos(t)^3','sin(t)^3',[0,2*pi])``

3、在[-2，0.5]，[0，2]上画隐函数 exp(x)+sin(x*y）=0的图

``ezplot('exp(x)+sin(x*y)',[-2,0.5,0,2])``

## 1.3flot('fun',lims)画图

fun是建立M文件或者是独立变量的x的字符串

``fplot('[tanh(x),sin(x),cos(x)]',2*pi*[-1,1,-1,1])``

## 1.4对数坐标图

``````x=logspace(-1,2);
loglog(x,exp(x),'-s')
grid on``````

## 2.1plot(x,y,z,线形)

``````t=0:pi/50:10*pi;
plot3(sin(t),cos(t),t)
rotate3d``````

``````x=-3:0.1:3;y=1:0.1:5;
[X,Y]=meshgrid(x,y);%为了产生矩阵
Z=(X+Y).^2;
plot3(X,Y,Z)``````

## 2.2surf(x,y,z)画出数据点（x,y,z）表示的曲面

``````x=-3:0.1:3;
y=1:0.1:5;
[X,Y]=meshgrid(x,y);
Z=(X+Y).^2;
surf(X,Y,Z)

## 3.2在图像的线上标注名称，gtext('名字')

``````x=linspace(0,2*pi,30);
y=sin(x);
z=cos(x);
plot(x,y,x,z);
gtext('sin(x)');gtext('cos(x)')``````

## 3.3定制坐标Axis([xmin,xmax,ymin,ymax,zmin,zmax])

``````x=linspace(0.0001,0.01,1000);
y=sin(1./x);
plot(x,y)
axis([0.005,0.01,-1,1])``````

## 3.4分割窗口subplot

``````x=linspace(0,2*pi,100);
y=sin(x); z=cos(x);
a=sin(x).*cos(x);b=sin(x)./(cos(x)+eps)
subplot(2,2,1);plot(x,y),title('sin(x)')
subplot(2,2,2);plot(x,z),title('cos(x)')
subplot(2,2,3);plot(x,a),title('sin(x)cos(x)')
subplot(2,2,4);plot(x,b),title('sin(x)/cos(x)');``````

## 特殊函数图像

1、极坐标图polar (theta弧度,rho极半径,s)

``````theta=linspace(0,2*pi),
rho=sin(2*theta).*cos(2*theta);
polar(theta,rho,'g')
title('Polar plot of sin(2*theta).*cos(2*theta)');``````

## 2、散点图、等值线平面图

``````[X,Y]=meshgrid(-2:.2:2,-2:.2:3);
Z=X.*exp(-X.^2-Y.^2);
[C,h]=contour(X,Y,Z);
clabel(C,h)
colormap cool``````

## 山峰的三维和二维等值线图。空间等值线图： contour 3(x,y,z,n)，n为等值线数

``````[x,y,z]=peaks;
subplot(1,2,1)
contour3(x,y,z,16,'s')
grid,   xlabel('x-axis'),ylabel('y-axis')
zlabel('z-axis')
title('contour3 of peaks');
subplot(1,2,2)
contour(x,y,z,16,'s')
grid,  xlabel('x-axis'), ylabel('y-axis')
title('contour of peaks');``````

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