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MATLAB 绘图

MATLAB 绘图. 二维图形. MATLAB 绘图. 符号函数画图 —ezplot & fplot ezplot(f,[a,b]) % 默认区间为 [-2pi, 2pi] ezplot(f,[xmin,xmax,ymin,ymax]) ezplot(x,y) % 在默认区间 0<t<2pi, 绘制 x=x(t),y=y(t) 的函数图。 ezplot(x,y,[tmin,tmax]). MATLAB 绘图. ezplot('cos(x)') ezplot('cos(x)', [0, pi])

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MATLAB 绘图

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  1. MATLAB绘图 二维图形

  2. MATLAB绘图 • 符号函数画图—ezplot & fplot ezplot(f,[a,b]) % 默认区间为 [-2pi, 2pi] ezplot(f,[xmin,xmax,ymin,ymax]) ezplot(x,y) %在默认区间0<t<2pi,绘制x=x(t),y=y(t)的函数图。 ezplot(x,y,[tmin,tmax])

  3. MATLAB绘图 ezplot('cos(x)') ezplot('cos(x)', [0, pi]) ezplot('1/y-log(y)+log(-1+y)+x - 1') ezplot('x^2 - y^2 - 1') ezplot('x^2 + y^2 - 1',[-1.25,1.25]); axis equal ezplot('x^3 + y^3 - 5*x*y + 1/5',[-3,3]) ezplot('x^3 + 2*x^2 - 3*x + 5 - y^2') ezplot('sin(t)','cos(t)') ezplot('sin(3*t)*cos(t)','sin(3*t)*sin(t)',[0,pi]) ezplot('t*cos(t)','t*sin(t)',[0,4*pi])

  4. Fplot 绘制函数在指定函数区间的图形 fplot(fun,lims,tol) %lims=[xmin,xmax] tol 默认为0.002. fplot('sin(1 / x)', [0.01 0.1],1e-3)

  5. MATLAB绘图 fplot(fun,lims,tol) % fun 必须是m文件或者独立变量为x的字符串，如果fun为[f1(x),f2(x),f3(x)]，则当输入[x1,x2]后，返回的是矩阵[f1(x1),f2(x1),f3(x1) f1(x2),f2(x2),f3(x2)] fplot('[tan(x),sin(x),cos(x)]',2*pi*[-1 1 -1 1])

  6. f = inline('abs(exp(-j*x*(0:9))*ones(10,1))'); fplot(f,[0 2*pi])

  7. MATLAB绘图 • 画点 plot(2,4, 'r*') • 画线 plot([0 1],[0 2]) x=2:2:8; plot([x;x],[zeros(1,length(x));cos(pi*x/20)], 'k') %axis([0 10 0 1])

  8. MATLAB绘图 画圆 theta=linspace(0,2*pi); plot(1+0.5*cos(theta),2+0.5*sin(theta)) axis equal %使图形对称 如何画具有不同半径的同心圆？

  9. MATLAB绘图 • 函数相对另一函数的图形绘制 theta=linspace(0,2*pi,101); plot(sin(theta),sin(2*theta+pi/4)) % 里萨如图形 axis off %隐去坐标轴

  10. MATLAB绘图 • 曲线族的绘制 例， 抛物线族 y =a^2-x^2, -5<x<5, a=1,2…5. x=-5:0.2:5; a=1:5; [xx,aa]=meshgrid(x.^2,a.^2); plot(x,aa-xx,’k’)

  11. MATLAB绘图

  12. MATLAB绘图 • 在一个图形界面中绘制多条曲线 y = 0.1*x^2 y=cos(x)^2 y=exp(-0.3x) x=linspace(0,3.5); plot(x,0.1*x.^2,’k’) hold on plot(x,cos(x).^2,’k’) plot(x,exp(-0.3*x),’k’)

  13. MATLAB绘图 • 基本二维绘图函数plot t=0:.1:2*pi; y=sin(t); plot(t,y) ,pause t=0:.1:2*pi; y=[sin(t); cos(t)]; plot(t,y) ,pause t=0:.1:2*pi; plotyy(t,sin(t),t,0.01*cos(t)) ,pause t=0:.1:2*pi; y=[sin(t); cos(t)]; plot(t,y) ,pause plot(t,sin(t),t,cos(t)) ,pause t=0:.1:2*pi; y1=sin(t); y2=cos(t); y3=sin(t).*cos(t); ,pause plot(t,y1,'-',t,y2,':',t,y3,'x') grid, xlabel('This is my X axis'), ylabel('My Y axis'), title('My First Plot')

  14. MATLAB绘图 • 图形注释和可视化提高 • 使用坐标轴，图形标题，曲线标注，填充区域和添加文本 • 改变轴、曲线和文本的属性 • 使用希腊字母、数学符号、上下标等

  15. MATLAB绘图 例 x=0:0.05:6; plot(x,cos(x),'k',x,1./cosh(x),'k',[4.73 4.73],[-1 1],'k') xlabel('x') ylabel('value of function') title('visualizaton of two intersecting curves') text(4.8,-.5,'x=4.73') text(2.1,.3,'1/cosh(x)') text(1.2,-.4,'cos(x)')

  16. MATLAB绘图 • 加图例—legend函数 legend函数不同于text函数，因为text函数可多次使用，而legend函数却只可用一次。Legend函数的参数个数与一个或多个plot函数绘制的不同线段个数相等。 x=0:.05:6; plot(x,cos(x), 'k-',x,1./cosh(x), 'k --') legend('cos(x) ', '1/cosh(x) ',3)

  17. MATLAB绘图 • plot中属性设置 x=-pi:pi/10:pi; y=tan(sin(x))-sin(tan(x)); plot(x,y,'-- rs', 'LineWidth',2, … 'MarkerEdgeColor','k', … 'MarkerFaceColor','g', … 'MarkerSize',10)

  18. MATLAB绘图 LineWidth 指定线条的粗细 MarkerEdgeColor 指定标记的颜色或填充标记(圆形，方形，金刚石形等)的边缘色 MarkerFaceColor 指定填充标记表面的颜色 MarkerSize 以点集为单位指定标记的大小

  19. MATLAB绘图 • set函数 x=0:.05:6; h=plot(x,cos(x),'k',x,1./cosh(x),'k',[4.73 4.73],[-1 1],'k'); text(4.8,-.5,'x=4.73','fontname','times','fontsize',14) text(2.1,.3,'1/cosh(x)','fontsize',16) text(1.2,-.4,'cos(x)','fontsize',16,'fontname','times') set(gca,'fontsize',14,'LineWidth',2) PropertyName={'LineWidth','LineWidth','LineWidth'}; PropertyValue={2.5,2.5,2.5;7,7,7;1,1,1}; set(h,PropertyName,PropertyValue) [legendhandle objecthandle]=legend('cos(x)','1/cosh(x)',3); set(objecthandle(1),'fontsize',14,'color','r')

  20. MATLAB绘图 • 调整坐标轴度量标记的位置和标签 x=-pi:.1:pi; y=sin(x); plot(x,y) set(gca, 'XTick',-pi:pi/2:pi) set(gca, 'XTickLabel',{'-pi', '-pi/2', '0', 'pi/2', 'pi'})

  21. x=0:.05:6; h=plot(x,cos(x),‘-b',x,1./cosh(x),‘--r',[4.73 4.73],[-1 1],'k'); xlabel('x'); ylabel('Value of Function') title('Visualization of two intersectting curves') text(4.8,-.5,'x=4.73','fontname','times','fontsize',14) text(2.1,.3,'1/cosh(x)','fontsize',16) text(1.2,-.4,'cos(x)','fontsize',16,'fontname','times') set(gca,'fontsize',14,'LineWidth',2) PropertyName={'LineWidth','LineWidth','LineWidth'}; PropertyValue={2.5,2.5,2.5;7,7,7;1,1,1}; set(h,PropertyName,PropertyValue) [legendhandle objecthandle]=legend('cos(x)','1/cosh(x)',3); set(objecthandle(1),'fontsize',14,'color','r')

  22. MATLAB绘图 • 增加希腊字母、上标下标和数学符号对图形进行注释 Omega1=linspace(1,2); beta=3; plot(Omega1,1+exp(-Omega1.^beta),'k') title('Plot of g_2 versus \Omega_1 for \beta=3') ylabel('g_2') xlabel('\Omega_1') text(1.2,1.2,'g_2=1+e^{-\Omega_1^\beta}','fontsize',16)

  23. MATLAB绘图 t=['\partial(f_ip)/\partialt=-\Sigma_{i=1}^n\partial(f_ip)/\partialx_i',... ' + 0.5\Sigma_{i=1}^n\Sigma_{j=1}^n\partial^2(b_{ij}p)/',... '\partialx_i\partialx_j']; gtext(t); gtext('Y(\omega)=\int_0^\infty y(t)e^{-j\omegat}dt'); t=['\partial(f_ip)/\partialt=-\Sigma_{i=1}^n\partial(f_ip)/\partialx_i',... ' + 0.5\Sigma_{i=1}^n\Sigma_{j=1}^n\partial^2(b_{ij}p)/',... '\partialx_i\partialx_j']; tt=str2mat(t,'Y(\omega)=\int_0^\infty y(t)e^{-j\omegat}dt'); [x,y]=ginput(1); text(x,y,tt)

  24. MATLAB绘图 • 作业 • 施加在弹簧上的力与C1成比例，其中 C1=0.5dt^3-1.5ht*dt^2+(1+ht^2)dt ht=h/t, dt=d/t, d为弹簧的挠度。当ht在1~3之间变化，增量为0.25，且dt在0~5之间变化时，画出C1随dt变化的曲线，标注曲线，并令y极限为8。结果如图

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