46.绘制椭圆,长轴为3.25,短轴为1.15
>> x=1.15*cos(t);y=3.25*sin(t);%y为长轴,x为短轴
>> subplot(2,2,1);plot(x,y);
>> axis off%不显示坐标轴
>> title('axis off')
>> subplot(2,2,2);plot(x,y);
>> axis image;%纵、横坐标等长刻度,坐标框紧贴数据范围
>> title('axis image')
>> subplot(2,2,3);plot(x,y);
>> axis equal;%纵、横坐标等长刻度
>> subplot(2,2,4);plot(x,y);
>> axis square;%产生方形坐标系
>> title('axis square');
47.分格线与grid指令
grid on(画出分格线);
grid off(不画分格线),缺省设置;
>> t=6*pi*(0:100)/100;
>> y=1-exp(-0.3*t).*cos(0.7*t);
>> tt=t(find(abs(y-1)>0.05));
>> ts=max(tt);
>> plot(t,y,'r-');
>> grid on;
>> axis([0,6*pi,0.6,max(y)]);
>> title('y=1-exp(-\alpha*t)*cos(\omega*t)');
>> hold on;
>> plot(ts,0.95,'bo');
>> hold off;
>> set(gca,'xtick',[2*pi,4*pi,6*pi],'ytick',[0.95,1,1.05,max(y)]);
>> grid on;
48.在正弦曲线上标注特殊值
>> t=(0:100)/100*2*pi;
>> y=sin(t);
>> plot(t,y);
>> text(3*pi/4,sin(3*pi/4),'\fontsize{16}\leftarrowsin(t)=.707');
>> text(pi,sin(pi),'\fontsize{16}\leftarrowsin(t)=0');
>> text(5*pi/4,sin(5*pi/4),'\fontsize{16}sin(t)=-.707\rightarrow','HorizontalAlignment','right')
%'HorizontalAlignment','right'设置图形标识为水平右对齐
>> t=0:900;
>> plot(t,0.25*exp(-0.005*t));
>> title('\fontsize{16}\itAe^{\alphat}');
>> text(300,.25*exp(-0.005*300),'\fontsize{14}\leftarrow0.25\ite^-0.005\itt_at\itt=300');
49.特殊图形(直方图(柱形图)bar)
>> x=-2.9:0.2:2.9;
>> bar(x,exp(-x.*x),'r');
例如:北京市从业人员统计
(累计式直方图一(竖着))
>> year=[1990 1995 2000];
>> people=[90.7 281.6 254.8;70.6 271 323.7;73.9 214.6 326.5];
>> bar(year,people,'stack');
>> legend('\fontsize{6}第一产业','\fontsize{6}第二产业','\fontsize{6}第三产业');
(累计式直方图二(横着))
>> barh(year,people,'stack');
>> legend('\fontsize{6}第一产业','\fontsize{6}第二产业','\fontsize{6}第三产业');
(分组式直方图一(竖着))
>> bar(year,people,'group');%分组式直方图
>> legend('\fontsize{6}第一产业','\fontsize{6}第二产业','\fontsize{6}第三产业');
(分组式直方图二(横着))
>> barh(year,people,'group');
>> legend('\fontsize{6}第一产业','\fontsize{6}第二产业','\fontsize{6}第三产业');
50.饼图指令pie
饼图指令pie用来表示各元素占总和的百分数。该指令第二输入变量是与第一变量同长的0-1向量,1使对应扇块突出。
>> a=[1,1.6,1.2,0.8,2.1];
>> subplot(1,2,1),pie(a,[1 0 1 0 0]),legend({'1','2','3','4','5'});
>> subplot(1,2,2),b=int8(a==min(a));
>> pie3(a,b);
>> colormap(cool);