第四节Matlab绘图功能一、二维图形1.plot函数线条选项：plot(x,y,LineSpec)或plot(x,y,'PropertyName',PropertyValue)【例1】在区间0≤X≤2内,绘制正弦曲线Y=sin(X).x=0:pi/100:2*pi;y=sin(x);plot(x,y,'r--')%%红色折线figure%%另开一图形plot(x,y,'linewidth',6);%%线条宽度3更复杂的例子x=-pi:pi/10:pi;y=tan(sin(x))-sin(tan(x));plot(x,y,'--rs','LineWidth',2,'MarkerEdgeColor','k',...'MarkerFaceColor','g','MarkerSize',10)【例2】同时绘制正、余弦两条曲线Y1=sin(x)和Y2=cos(x)x=0:pi/100:2*pi;y1=sin(x);y2=cos(x);plot(x,y1,x,y2)plot函数还可以为plot(x,y1,x,y2,x,y3,…)形式，以公共向量x为X轴,分别以y1,y2,y3,…为Y轴,在同一幅图内绘制出多条曲线。holdon非常有用,常用在一个图上画多个图形.2.阶梯图形stairs函数x=[-2.5:0.25:2.5];y=exp(-x.*x);stairs(x,y);title('stairsplot');3.条形图形barx=[-2.5:0.25:2.5];y=exp(-x.*x);bar(x,y);%%绘制条形图命令二维绘图函数小结二、三维图形【例3】绘制三维螺旋曲线t=0:pi/50:10*pi;y1=sin(t),y2=cos(t);plot3(y1,y2,t);title('helix');xlabel('sin(t)'),ylabel('cos(t)'),zlabel('t');grid;%%给出网格.2.mesh函数函数格式：mesh(x,y,z)2.meshc函数函数格式：meshc(x,y,z)[X,Y]=meshgrid(-3:.125:3);Z=X.*exp(-X.^2-Y.^2);contourf(X,Y,Z);xlabel('x-axis');ylabel('y-axis');zlabel('z-axis');title('contour3ofpeaks')colorbar%%加颜色条4.surf函数函数格式:surf(x,y,z)[X,Y]=meshgrid(-2:0.2:2,-2:0.2:2);Z=X.*exp(-X.^2-Y.^2);surf(X,Y,Z)xlabel('x-axis');ylabel('y-axis');zlabel('z-label')5.等高线图通过contour3绘制。【例6】多峰函数peaks的等高线图[x,y,z]=peaks(30);%%matlab定义的peaks函数contour3(x,y,z,16);xlabel('x-axis');ylabel('y-axis');zlabel('z-axis');title('contour3ofpeaks')实验内容