MATLAB作业

第一次作业

1.shortProblems

%标量变量生成

a=10

b=2.5*(10^23)

c=2+3*i

d=exp(j*2*pi/3)

%向量生成

aVec=[3.14 15 9 26]

bVec=[2.71 8 28 182]'

cVec=5:-0.2:-5

dVec=logspace(0,1,101)

eVec='Hello'

%矩阵变量

aMat=2*ones(9,9)

B=[1 2 3 4 5 4 3 2 1];

bMat=diag(B)

C=[1:100];

cMat=reshape(C,10,10)

dMat=NaN*ones(3,3)

E=[13 -22 -1 10 5 -87];

eMat=reshape(E,2,3)

F=-3+fix(3*rand(1,15));

fMat=reshape(F,5,3)

%标量方程

x=1/(1+exp(-(a-15)/6))

y=(sqrt(a)+b^(1/21))^pi

z=log(real((c+d)*(c-d))*sin(a*pi/3))/(c*conj(c))

%向量方程计算

xVec=1/(2.*pi.*(2.5.^2))*exp((-cVec.^2)./(2.*(2.5.^2))) yVec=sqrt((aVec'.^2)+bVec.^2)

zVec=log10(1./dVec)

%矩阵运算

xMat=(aV ec*bVec)*(aMat^2)

yMat=bVec*aVec

zMat=det(cMat)*((aMat*bMat)')

%一般运算及元素索引

cSum=sum(cMat)

eMean=mean(eMat,2)

eMat(1,:)=[1 1 1]

cSub=cMat(2:9,2:9)

lin=1:20;

lin(2:2:end)=-lin(2:2:end)

r=rand(1,5)

r(find(r<0.5))=0

2.twoLinePlot

figure;

t=0:pi/100:2*pi;

plot(t,sin(t));

hold on;

plot(t,cos(t),'r:');

xlabel('Time(s)');

ylabel('Function value');

title('Sin and Cos');

legend('sin','cos','location','NorthEast'); xlim([0 2*pi]);

ylim([-1.4 1.4]);

3.calculateGrades

R=xlsread('testdata.xls');

ans=R(1:5,:)

grades=R(:,2:end);

ans=mean(grades)

meanGrades=nanmean(grades)

meanMatrix=repmat(meanGrades,size(grades,1),1) curvedGrades=3.5*(grades./meanMatrix);

ans=nanmean(curvedGrades)

curvedGrades(find(curvedGrades>5))=5;

totalGrade=(ceil(nanmean(curvedGrades')))'

letters='FDCBA';

for k=1:length(totalGrades)

switch totalGrades(k)

case 1

Grades(k)=letters(1);

case 2

Grades(k)=letters(2);

case 3

Grades(k)=letters(3);

case 4

Grades(k)=letters(4);

case 5

Grades(k)=letters(5);

end

end

disp(['Grades:',letterGrades]);

4.encrypt

original='This is my top secret message!';

encodeouter=randperm(length(original));

encoded=original(encodeouter);

temp=[encodeouter;1:length(original)]';

temp=sortrows(temp)

decodeouter=temp(:,2);

decoded=encoded(decodeouter);

disp(['Original: ' original]);

disp(['Encoded : ' encoded]);

disp(['Decoded : ' decoded]);

correct=strcmp(original,decoded);

disp(['Decoded correctly (1 true;0 false): ' num2str(correct)]);

5.throwBall

clear all;

h=1.5;

g=9.8;

v=4;

a=45;

t=linspace(0,1,1000);

x_t=v*cos(a*pi/180)*t;

plot(t,x_t,'r');

hold on;

t=linspace(0,1,1000);

y_t=h+v*sin(a*pi/180)*t-1/2*g*t.^2;

plot(t,y_t);

t0=min(find(y_t<=0));

x0=x_t(t0);

disp(x0);

xlabel('时间轴');

ylabel('函数');

title('抛球模型');

legend('x(t)','y(t)');

disp(['小球在',num2str(x0),'处撞到地面']);

hold on;

plot([0 max(x_t)],[0 0],'k--');