同济大学matlab课程练习题答案

1、同济大学 matlab 课程练习题答案关晓飞第一章 初识 matlab题目 1x1=input(x1=);x2=input(x2=);x3=input(x3=);x4=input(x4=);x5=input(x5=);x6=input(x6=);x7=input(x7=);a=x1/x5;b=x3/(x2-x1)0.85;c=1-0.36*(x4/x2)(-0.56);d=2.62*c1.5;e=(x4/x2)1.16;f=(1-d*e)/(x6*x7)0.5;y=174.42*a*b*f题目 2略题目 3 help lookfor lookfor Search all MATLAB file

2、s for keyword.lookfor XYZ looks for the string XYZ in the first comment line(the H1 line) of the HELP text in all MATLAB files found on MATLABPATH (including private directories). For all files in which amatch occurs, lookfor displays the H1 line.For example, lookfor inverse finds at least a dozen m

3、atches, including the H1 lines containing inverse hyperbolic cosine two-dimensional inverse FFT, and pseudoinverse.Contrast this with which inverse or what inverse, which run more quickly, but which probably fail to find anything because MATLAB does not ordinarily have a function inverse.lookfor XYZ

4、 -all searches the entire first comment block of each MATLAB file.In summary, WHAT lists the functions in a given directory,WHICH finds the directory containing a given function or file, and lookfor finds all functions in all directories that might havesomething to do with a given key word.题目 4n=inp

5、ut(n=);sum(1:n)prod(1:n)题目 5 linspace(0,360,9)ans =0 45 90 135 180 225 270 315 360题目 7n=input(n=)format bankn第二章矩阵的建立题目 1.spiral 产生螺旋矩阵例：spiral(3)ans=7 8 96 1 25 4 3题目 2.(1)1 2;3 4+10-2ians =12.0000 - 2.0000i14.0000 - 2.0000i11.0000 - 2.0000i13.0000 - 2.0000i(2)1 2;3 4.*0.1 0.2;0.3 0.4 ans =0.1000 0

6、.40000.90001.60003) 1 2;3 4.20 10;9 2ans =20.00003.0000（4）exp（1 2;3 4）ans =5.00000.5000%自然对数的 1、2、3、4 乘方2.7183 7.389120.0855 54.5982（5）1 2;3 4.2ans =14916（6）sum（1 2;3 4） ans =4 6(7)prod(1 2;3 4)%每一列的所有行相加ans =3（8）a,b=min（10a =10b =1（9）abs（1 2;3 4-pi）ans =2.14160.1416（10）820;30 40)%a代表每一列的最小值， b 代表该值

7、所在的行数201%绝对值1.14160.8584linspace（3,4,5）%生成 3 到 4 均匀的 5 个数ans =3.00003.2500 3.5000 3.75004.0000%提取第 2 列(11)A=1 2;3 4;sort(A(:,2) ans =24题目 3.A=1,2,3,4;4,3,2,1;2,3,4,1;3,2,4,1A =1234432123413241A(5,6)=5A =123400432100230 题目 4 示例： A=3 -1;-1 3 A =3-1 X,D=eig(A) X =-0.7071-0.7071D =20 题目 5 A =-13-0.70710

8、.7071043 -1-1 32Aans =10-6-6102.A ans =8.00000.50000.50008.0000题目 6(1)A=magic(6)A =351626192433272123253192222720828331710153053412141643629131811c=A(2,1)c =3（2）t = 2:2:6;B = A(t,:);BB =33272123258283317101543629131811（3）A(: , end,2:end-1,1)ans =241626193525327212332092222731152833171081653412143011

9、362913184(4)A(:,1 3 4 5 6)ans =356261924372123253122227208331710153034121416429131811题目 7 ones(4,5) ans =11111111111111111111rand(3,4)ans =0.81470.91340.27850.96490.90580.63240.54690.15760.12700.09750.95750.9706 eye(3)ans =100010001题目 8A=0:99;A=reshape(A,10,10)010203040506070809011121314151617181912

10、1222324252627282 9231323334353637383934142434445464748494515253545556575859561626364656667686967172737475767778797818283848586878889891929394959697989 99A=magic(3) 题目 9 A =816357492A(2,:)=A(2,:)*2A =81661014492A(1,:)=A(1,:)+A(3,:)*(-2)A =0 -17 261014492题目 10A=1,3,5;5,8,3;6,1,6;B=3,6;9,5;8,2;C=3,3,9;

11、4,0,6;D=2:6; A,Bans =135365839561682A;Cans =135583616339406A,B;Dans =13536583956168223456A=ones(6,7)A =111111111111111111111111111111111111111111题目 11for i=1:6for j=1:7A(i,j)=i+j;endendAA =2345678345678945678910567891011678910111278910111213%本题还有多种方法第三章符号计算题目 1略题目 2 sym(0,3)ans =0.3 sym(0.3)%符号工具箱得出

12、更精确的解ans =3/10题目 3 syms x s f=x5+3*x4+4*x3+2*x2+3*x+6;g=(s-1)/(s+1); f(x)=compose(f,g,x,s) f(x) =(3*(s - 1)/(s + 1) + (2*(s - 1)2)/(s + 1)2 + (4*(s - 1)3)/(s + 1)3 + (3*(s - 1)4)/(s + 1)4 + (s - 1)5/(s + 1)5 + 6 simplify(f(x) ans =19 - (72*s4 + 120*s3 + 136*s2 + 72*s + 16)/(s + 1)5题目 4 sum(sym(2).1:

13、64) ans =230题目 5f=sym(cos(4*a)-4*cos(2*a)+3);simplify(f) ans =8*sin(a)4题目 6 f=sym(3*x+2/3)10);expand(f) ans =59049*x10 + 131220*x9 + 131220*x8 + 77760*x7 + 30240*x6 + 8064*x5+ (4480*x4)/3 + (5120*x3)/27 + (1280*x2)/81 + (5120*x)/6561 + 1024/59049所以系数最大的项是 131220*x9 和 131220*x8题目 7 syms a x factor(a*

14、(sin(x)2-(2*a2-a+1)*sin(x)+2*a-1) ans =(sin(x) - 2*a + 1)*(a*sin(x) - 1)第四章极限与导数题目 1(1) syms x;lim1=limit(cos(x)-exp(-x2/2)/x4,x,0)lim1 =-1/12(2) syms x t;lim2=limit(1+2*t/x)3*x,x,inf)lim2 =Inf + imag(t)*6*i(3) syms x;lim3=limit(1/x,x,0,right)Lim3 =Inf(4) syms x;lim4=limit(2x-log(2x)-1)/(1-cos(x),x,

15、0)Lim4 =log(2)2题目 2 syms x;lim=limit(exp(x)-1-x)/x2,x,0) lim =1/2题目 3 syms x;lim=limit(x0.5-2(-1/x),x,0,right)lim =0题目 4 syms x;lim=limit(atan(x)/(1+x2),x,pi,left) lim =atan(pi)/(pi2 + 1)题目 5 y=7*x3-2*x+3;z=diff(y,2);x=1;eval(z)ans =42题目 6 syms x y;z=exp(x)*sin(2*y)+log(x)*cos(2*y);f=diff(z,y)f =2*c

16、os(2*y)*exp(x) - 2*sin(2*y)*log(x)题目 7 syms x y t;x=t2*sin(t);y=2*t*cos(t);f=diff(y)/diff(x)f =(2*cos(t) - 2*t*sin(t)/(t2*cos(t) + 2*t*sin(t)题目 8 syms x;lim=limit(3x+9x)(1/x),x,inf)lim =9题目 9 syms x;lim=limit(1+x)(1/x),x,0)lim =exp(1)题目 10 syms x;y=(x-1)*(x-2)/(x-3)/(x-4)0.5;f1=diff(y,1),f2=diff(y,2

17、),f3=diff(y,3)f1 =(x - 1)/(x - 3)*(x - 4) + (x - 2)/(x - 3)*(x - 4) - (x - 1)*(x- 4)/(2*(x- 2)/(x - 3)*(x - 4)2) - (x - 1)*(x - 2)/(x - 3)2*(x- 1)*(x - 2)/(x - 3)*(x - 4)(1/2)f2 =(2/(x - 3)*(x - 4) - (2*(x - 1)/(x - 3)*(x - 4)2) - (2*(x - 1)/(x- 3)2*(x - 4) - (2*(x - 2)/(x - 3)*(x - 4)2) - (2*(x - 2

18、)/(x - 3)2*(x- 4) + (2*(x - 1)*(x - 2)/(x - 3)*(x - 4)3) + (2*(x - 1)*(x - 2)/(x- 3)2*(x - 4)2) + (2*(x - 1)*(x - 2)/(x - 3)3*(x - 4)/(2*(x -1) *(x - 2)/(x - 3)*(x - 4)(1/2) - (x - 1)/(x - 3)*(x - 4) + (x- 2)/(x - 3)*(x - 4) - (x - 1)*(x - 2)/(x - 3)*(x - 4)2) - (x -1)*(x - 2)/(x - 3)2*(x - 4)2/(4*(

19、x - 1)*(x - 2)/(x - 3)*(x -4)(3/2)f3 =(3*(x - 1)/(x - 3)*(x - 4) + (x - 2)/(x - 3)*(x - 4) - (x - 1)*(x- 2)/(x - 3)*(x - 4)2) - (x - 1)*(x - 2)/(x - 3)2*(x -4)3)/(8*(x - 1)*(x - 2)/(x - 3)*(x - 4)(5/2)- (6/(x -3)*(x- 4)2) + 6/(x - 3)2*(x - 4) - (6*(x - 1)/(x - 3)*(x - 4)3) - (6*(x- 1)/(x - 3)2*(x -

20、4)2) - (6*(x - 1)/(x - 3)3*(x - 4) - (6*(x -2) )/(x - 3)*(x - 4)3) - (6*(x - 2)/(x - 3)2*(x - 4)2) - (6*(x - 2)/(x- 3)3*(x - 4) + (6*(x - 1)*(x - 2)/(x - 3)*(x - 4)4) + (6*(x - 1)*(x- 2)/(x - 3)2*(x - 4)3) + (6*(x - 1)*(x - 2)/(x - 3)3*(x - 4)2)+ (6*(x - 1)*(x - 2)/(x - 3)4*(x - 4)/(2*(x - 1)*(x - 2

21、)/(x -3) *(x - 4)(1/2) - (3*(x - 1)/(x - 3)*(x -4) + (x - 2)/(x - 3)*(x- 4) - (x - 1)*(x - 2)/(x - 3)*(x - 4)2) - (x - 1)*(x - 2)/(x -3)2*(x - 4)*(2/(x - 3)*(x - 4) - (2*(x - 1)/(x - 3)*(x - 4)2) -(2*(x - 1)/(x - 3)2*(x - 4) - (2*(x - 2)/(x - 3)*(x - 4)2) - (2*(x - 2)/(x - 3)2*(x - 4) + (2*(x - 1)*(

22、x - 2)/(x - 3)*(x - 4)3) + (2*(x - 1)*(x - 2)/(x - 3)2*(x - 4)2) + (2*(x - 1)*(x - 2)/(x - 3)3*(x- 4)/(4*(x - 1)*(x - 2)/(x - 3)*(x - 4)(3/2)题目 11 syms x;y=x*log(x);diff(y,10)ans = 40320/x9题目 12 syms x;y=exp(-2*x);taylor(y,x,0,order,6)ans =- (4*x5)/15 + (2*x4)/3 - (4*x3)/3 + 2*x2 - 2*x + 1题目 13 syms

23、 x;y=x/sin(x);f=taylor(y,x,2,order,5),ezplot(f)(2*(cos(2)2/sin(2)2 + 1/2)/sin(2) - cos(2)/sin(2)2)*(x - 2)2 - (cos(2)/(3*sin(2) + (cos(2)*(cos(2)2/sin(2)2 + 1/2)/sin(2)/sin(2) - (2*(cos(2)2/(3*sin(2)2) + (cos(2)*(cos(2)/(3*sin(2) + (cos(2)*(cos(2)2/sin(2)2 + 1/2)/sin(2)/sin(2) + 5/24)/sin(2)*(x- 2)4

24、 - (2*cos(2)/sin(2)2 - 1/sin(2)*(x - 2) - (x -2)3*(2*(cos(2)/(3*sin(2) + (cos(2)*(cos(2)2/sin(2)2 +1/2)/sin(2)/sin(2) - (cos(2)2/sin(2)2 + 1/2)/sin(2) + 2/sin(2)题目 14 syms x1 x2 x3 x4 x5 x6 x7;a=x1/x5;b=x3/(x2-x1)0.85;c=1-0.36*(x4/x2)(-0.56);d=2.62*c1.5;e=(x4/x2)1.16;f=(1-d*e)/(x6*x7)0.5;y=174.42*a*

25、b*f; f1=diff(y,x1);f2=diff(y,x2);f3=diff(y,x3);f4=diff(y,x4);f5=diff(y,x5);f6=diff(y,x6);f7=diff(y,x7);x1=0.1;x2=0.3;x4=0.1;x5=1.5;x6=16;x7=0.7 5; eval(f1),eval(f2),eval(f3),eval(f4),eval(f5),eval(f6),eval(f7)ans =(649*x3)/(80*(5*x3)(3/20) + (63*(5*x3)(17/20)/0ans =(62824*(5*x3)(17/20)/5967 - (649*x

26、3)/(80*(5*x3)(3/20) ans =31763/(200*(5*x3)(3/20)ans =-(*(5*x3)(17/20)/57571ans =-(21*(5*x3)(17/20)/00ans =-(137*(5*x3)(17/20)/3264ans =-(137*(5*x3)(17/20)/72第五章 程序编制题目 1略题目 2function f=fib(n)if n=1|n=2 %“| ”是或者f=1;elsef=fib(n-1)+fib(n-2);end题目 3 function a=countwords(s)d=length(s);n=1;x=0;while n0)&

27、(isempty(ounce)=1)&(isempty(kerra)=1)ounce=kilogram*1000/28.3495,kerra=kilogram*1000/0.2,endif ounce0&(isempty(kilogram)=1)&(isempty(kerra)=1) kilogram=ounce*28.3495/1000, kerra=ounce*5*28.3495 endif kerra0&(isempty(ounce)=1)&(isempty(kilogram)=1) ounce=kerra/(5*28.3495),kilogram=kerra/5000,end%每次输入

28、其中一个，输出另两个的换算结果题目 5y=input(enter a year:);m=input(enter a month:);if (mod(y,400)=0)|(mod(y,4)=0)&(mod(y,100)=0)switch m,case1,3,5,7,8,10,12nday=31;case4,6,9,11nday=30;otherwise nday=29;endelseswitch m,case1,3,5,7,8,10,12nday=31;case4,6,9,11nday=30;otherwise nday=28;end endnday=nday题目 6s=input(,s);a=

29、s(1:4);y=str2num(a);b=s(6:7);M=str2num(b);c=s(9:10);D=str2num(c);C=floor(y/100);% 世纪数Y=mod(y,100);%年份后两位 w=mod(floor(C/4)-2*C+Y+floor(Y/4)+floor(13*(M+1)/5)+D-1),7) % Zeller 公式该年的 1，2 月按 13，14 计算。题目 7m=input();if m1500)&(m4500)&(m9000)&(m35000)&(m80000t=45+300+900+6000+15750+0.45*(m-80000)endt第六章 算法

30、入门%习题一%查键盘字符对应的 ASCII 码clear,clc% 清空变量和屏幕a=input( 请输入您的要加密的字符： n,s); % 输入加密字符n=length(a);% 计算字符长度for i=1:n,if (a(i)=65 & a(i)=97 & a(i)=87 & a(i)=118 & a(i)=2A1=cell(n,1);o=0;for i=1:nA1i,1=input(one of the words:,s);endj=1;while jns=A1j,1;b=length(s);k=j+1;while k=nt=A1k,1;d=length(t);u=setxor(s,t)

31、;if (b=d)&(length(u)=2)|(b=d+1)|(d=b+1)&(length(u)0)0X(S(i,m)=0;endendfor n=1:9%列不重复if S(n,j)0X(S(n,j)=0;endendB=Aa,b;for p=1:3%宫不重复for q=1:3if B(p,q)0X(B(p,q)=0;endendendend if sum(X0)=1S(i,j)=sum(X);endendendendS %本题答案只用了书上的方法，且只能够解出书上例题难度的题目第八章 图形的绘制题目 1x=linspace(0,4*pi,8000);y1=sin(x);y2=cos(x)

32、;y4=0;plot(x,y1,k);hold on;plot(x,y2, k);xlabel( x);ylabel( y);plot(x,y4,k);hold on;plot(x,y2, k);xlabel( x);ylabel( y);plot(x,y4,;k);plot(y4,x, k);title( y1=sin(x) y2=cos(x) );x1=linspace(0,0.5*pi,1000);r)y3=sin(x1);fill(x1,pi/2,y3,0,题目 2Subplot(2,2,1);x=0:pi/60:2*pi,plot(x,sin(2*x);Subplot(2,2,2);

33、y=0:pi/60:0.499*pi;plot(y,tan(y);Subplot(2,2,3);plot(x,log(x);Subplot(2,2,4);plot(x,exp(log(10)*x);题目 3X=213,387,220,280,280,180;Pie3(x)题目 3X=1:6;Y=213,387,220,280,280,180Bar(x,y),set(gca, XTicklabel , 计算机系 ; 外语系 ; 音乐系 美术系 ; 中文系 ; 理学院 ),Set(gca, XTick ,1:6),xlabel(专业 ), ylabel( 人数 ),title(专业学生分布 )%这

34、样做出的柱状图就跟 excel 差不多题目 4x=linspace(-3,3);y=linspace(-2,2);X,Y=meshgrid(x,y); f=X.2+(abs(X).*exp(Y)./(X.4+1);Mesh(X,Y,f)% 注意矩阵维度要一样题目 5 t=linspace(0,2*pi); x=sin(t);y=t.2+exp(t);comet(x,y) 题目 6(a) theta=0:0.01:4*pi; rho=cos(3.5.*theta); polar(theta,rho);(b) theta=0:0.01:6*pi; rho=sin(theta)./theta; po

35、lar(theta,rho);(c) theta=0:0.01:2*pi;rho=1-(cos(7.*theta).3; polar(theta,rho);题目 7function qiu(R)axis(equal);% 横纵坐标相等使其看起来更圆 a=linspace(0,2*pi);b=linspace(0,2*pi);A,B=meshgrid(a,b);X=R.*cos(B).*cos(A);Y=R.*cos(B).*sin(A);Z=R.*sin(B);mesh(X,Y,Z) function xuanzhuanqumian1(a,b,c)R=linspace(1,4);T=linspace(0,2*pi);r,t=meshgrid(R,T);x=a.*r.*cos(t);y=b.*r.*sin(t);z1=c.*s