第二次作业

第二次作业
1.semilog plot ： 程序：
clear all ; x=1:1:5;
y=[15,25,55,115,144];
semilogy(x,y,'rs--','MarkerFaceColor','g','LineWidth',2,'MarkerEdgeCo lor','k','MarkerSize',10); xlabel('years');
ylabel('number of students'); title('growth trend'); xlim([0 6]);
运行结果：
012
3456
10
1
10
2
10
3
years
n u m b e r o f s t u d e n t s
growth trend
2.bar graph ： 程序：
clear all ; x=1:1:5; y=rand(1,5);
bar(x,y,'r');
title('Bar graph of 5 random values');
运行结果：
12345
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Bar graph of 5 random values
3.插入和面绘制： 程序：
clear all ; z0=rand(5,5); x=1:5;
[x0,y0]= meshgrid(x,x); y=1:0.1:5;
[x1,y1]= meshgrid(y,y); %meshgrid 生成绘制3-D 图形所需的网格数据 z1=interp2(x0,y0,z0,x1,y1);
surf(z1); %surf 命令绘制得到的是着色的三维曲面
shading interp ; %shading interp 会区分每个线型区域 的颜色，并且插入与其相近的颜色
colormap(hsv); hold on ;
contour(z1); %绘制二维等值线图 colorbar; caxis([0 1]);
hold off ;
运行结果：
20
40
60
20
40
60
00.20.40.60.81
00.10.2
0.30.40.50.60.70.80.9
1
4.使用find ： 程序：
function ind=findNearest(x,desiredVal) c=abs(x(:)-desiredVal); ind=x(find(c(:)<1));
脚本: x=1:5
desiredVal=2.5
ind=findNearest(x,desiredVal)
运行结果： x =
1 2 3 4 5
desiredVal =
2.5000
ind =
2 3
5.循环和流程控制
程序：
function loopTest(N)
for i=1:N
if mod(i,2)==0&&mod(i,3)~=0 %如果i能被2整除不能被3整除
disp(['',num2str(i),' is divisible by 2']);
else if mod(i,3)==0&&mod(i,2)~=0 %如果i能被3整除不能被2整除 disp(['',num2str(i),' is divisible by 3']);
else if mod(i,3)==0&&mod(i,2)==0 %如果i能被2整除能被3整除 disp(['',num2str(i),' is divisible by 2 AND 3']);
else
disp(['',num2str(i),' is NOT divisible by 2 AND 3']);
end
end
end
end
运行结果：
>> loopTest(6)
1 is NOT divisible by
2 AND 3
2 is divisible by 2
3 is divisible by 3
4 is divisible by 2
5 is NOT divisible by 2 AND 3
6 is divisible by 2 AND 3
6.平滑器：
程序：
function smoothed=rectFilt(x,width)
if(mod(width,2)==0)
width %选择width为奇数
end;
for n=1:length(x)
if n<3 || n>length(x)-2
smoothed(n)=x(n);%边缘的点保持不动
else
smoothed(n)=mean(x((n-2):(n+2)));%平滑算法end
end
脚本:
x=xlsread('noisyData.xls');
width=11;
smoothed=rectFilt(x,width);
figure;
plot(x,'--','lineWidth',2);%plot x
hold on;
plot(smoothed,'r','lineWidth',2);%plot smoothed hold off;
xlabel('Index');
ylabel('Data value');
title('Smoothing Demonstration');
legend('Original Data','Smoothed');
运行结果：
10203040
5060708090100
-1.5-1
-0.5
0.5
1
1.5
Index
D a t a v a l u e
Smoothing Demonstration
Original Data Smoothed
7.绘制圆的函数 a.同心圆
程序：function [x,y]=getCircle(center,r)
t=-2*pi:0.01:2*pi for i=1:length(t) a=t(i);
x(i)=r*cos(a)+center(1); y(i)=r*sin(a)+center(2); end
脚本:
center=[0 0];
[x,y]=getCircle(center,1);hold on plot(x,y,'linewidth',4,'color','b'); [x,y]=getCircle(center,4);hold on plot(x,y,'linewidth',4,'color','k'); [x,y]=getCircle(center,7);hold on plot(x,y,'linewidth',4,'color','g'); [x,y]=getCircle(center,10);hold on plot(x,y,'linewidth',4,'color','y'); [x,y]=getCircle(center,13);hold on
plot(x,y,'linewidth',4,'color','r');
axis equal;
运行结果：
10
5
-5
-10
-15-10-5051015
b.olympic的logo
程序：
figure;
r=0.5;
[x,y]=getCircle([-1 0],r);hold on
plot(x,y,'linewidth',5,'color','b');
[x,y]=getCircle([0 0],r);hold on
plot(x,y,'linewidth',5,'color','k');
[x,y]=getCircle([0.5 -0.4],r);hold on
plot(x,y,'linewidth',5,'color','g');
[x,y]=getCircle([-0.5 -0.4],r);hold on
plot(x,y,'linewidth',5,'color','y');
[x,y]=getCircle([1 0],r);hold on
plot(x,y,'linewidth',5,'color','r');
axis equal;
运行结果：
10
5
-5
-10
-15-10-5051015。