matlab二维三维画图

二维画图

1. 画出函数f(x)?2x3?9x2?12x?3.解：x1=linspace(-20,20,20);

y1=2.*x1.^3-9.*x1.^2+12.*x1-3; plot(x1,y1)

结果：

1.5x 10410.50-0.5-1-1.5-2-2032-15-10-505101520

2. 画出函数f(x)?x.解：x1=linspace(-5,5,200);

y1=x1.^(2/3); plot(x1,y1,'.r')

结果：

32.521.510.50-0.5-1-1.5-5-4-3-2-1012345

?2x?1,x?0画出f(x)?，3. ?2?x?1,x?0

解：x1=linspace(0,1/2,200);

x2=linspace(-4/5,0,200); y1=2.*x1-1; y2=x2.^2-1;

plot(x1,y1,x2,y2)

结果：

0-0.1-0.2-0.3-0.4-0.5-0.6-0.7-0.8-0.9-1-0.8-0.6-0.4-0.200.20.40.6

4. 画出方程：x3?y3?3xy?0解：ezplot('x.^3+y.^3-3.*x.*y=0',[-1,1,-1,1]) 结果：

x3+y3-3 x y=010.80.60.40.20-0.2-0.4-0.6-0.8-1-1y-0.8-0.6-0.4-0.20x0.20.40.60.81

?x?5t2画出图形?5.

y?2t3?

解：ezplot('5.*t.^2','2.*t.^3',[-1,1]) 结果：

x = 5 t2, y = 2 t321.510.50-0.5-1-1.5-2y00.511.522.5x33.544.55

6.在同一坐标系下画出下列函数的曲线图，并进行详细标注。 1) y?0.2e0.1x?sin(0.5x) y?0.2e0.1x?cos(0.5x)，区间[0.2?] 解：X=linspace(0,100,2*pi);

subplot(2,1,1)

fplot('0.2.*exp(0.1.*x)+sin(0.5.*x)',X) title('1.y=0.2e^(0.1x)+sin(0.5x)') subplot(2,1,2)

fplot('0.2.*exp(0.1.*x)+cos(0.5.*x)',X,'b*:') title('2.y=0.2e^(0.1x)+cos(0.5x)')

结果：

1.y=0.2e(0.1x)+sin(0.5x)21.510.50-0.5024681012141618202.y=0.2e(0.1x)+cos(0.5x)210-102468101214161820

2) y2?x与y?x2相交的部分 解：ezplot('x^2',[-1,1,-1,1])

hold on

ezplot('y.^2-x',[-1,1,-1,1]) text(-0.8,0.4,'y=x^2') text(0.4,0.8,'y^2=x')

10.80.60.40.20-0.2-0.4-0.6-0.8-1-1-0.8-0.6-0.4-0.20x0.20.40.60.81y=x2y2=xy

x2y223x32??1与y?x?的相交部分 3)

16733解：ezplot('x.^2/16+y.^2/7-1',[-4,4,-3,3])

hold on

ezplot('2/3*x^(3/2)-x^3/3-y') text(0,-2.5,'x^2/16+y^2/7=1') text(0,0,'y=2/3x^(3/2)-x^3/3')

结果：

3210y=2/3x(3/2)-x3/3y-1-2x2/16+y2/7=1-3-4-3-2-10x1234

7.在同一页上画出四幅下列图像，并且要求详细标注。 1) 星形线 x?y?2

2) 心形线 x2?y2?2x?2x2?y2 3) 伯努利双纽线1 (x2?y2)2?2(x2?y2) 4) 伯努利双纽线2 (x2?y2)2?4xy 解：subplot(2,2,1)

syms x1 y1

z1=x1.^(2/3)+y1.^(2/3)-2^(2/3); ezplot(z1,[0,2,0,2]);

title('1.x^(2/3)+y^(2/3)=2^(2/3)') subplot(2,2,2) syms x2 y2

z2=x2.^2+y2.^2+2.*x2-2*sqrt(x2.^2+y2.^2); ezplot(z2,[-5,1,-3,3]);

title('2.x^2+y^2+2x=2sqrt(x^2+y^2)')

232323