MATLAB基礎(chǔ)與應(yīng)用教程習(xí)題答案作者蔡旭暉劉衛(wèi)國蔡立燕答案

1、第1章一、思考題4. ( 1) B=A(2:5,1:2:5)(2) A(7)=(3) A=A+30(4) size(A)( 5) t(find(t=0)=eps(6) t=reshape(x,3,4)(7) abs(matlab)(8) char(93)5. A=97,67,34,10;-78,75,65,5;32,5,-23,-59;0,-12,54,7(1) B=A(1:3,:)C=A(:,1:2)D=A(2:4,3:4)E=B*C(2) A(find(A=50 & A120gz=dj*120+*dj*(h-120);elseif h60gz=dj*h-700;elsegz=dj*h;en

2、dformat bank;display(gh,gz)3.循環(huán)結(jié)構(gòu)n=input( input n: );s=0;for k=1:ns=s+1/k2;enddisplay(sqrt(s*6)向量運(yùn)算n=input( input n: );k=1:n;display(sqrt(sum(1./k.2)*6)4.y=0;k=0;while y=1e-5 & k500x0=x;x=a/(b+x0);k=k+1;enddisplay(k,x);display(-b+sqrt(b2+4*a)/2,(-b-sqrt(b2+4*a)/2);6.y=fun(40)/(fun(30)+fun(20)(1)函數(shù)文件

3、 function f=fun(n) f=n+log(n2+5);(2)函數(shù)文件function f=fun(n) a=1:n;f=sum(a.*(a+1);第3章一、思考題4.t=0:;y=sqrt(3)/2*exp(-4*t).*sin(4*sqrt(3)*t+pi/3);5.x=-10:10;y=linspace(-6,6,size(x,2)z=x.3+3*x.*y.2;plot3(x,y,z)6.x=100:100:400;y=100:100:400;z=636,697,624,478;698,712,630,478;680,674,598,412;662,626,552,334;X,

4、Y=meshgrid(x,y);mesh(X,Y,z)二、實驗題1.( 1 ) x=-10:10;plot(x,x-x.3/3/2)( 2 ) plot(x,exp(-x.*x/2)/2/pi)( 3) x=-8:8;plot(x,sqrt(64-x.*x)/2)( 4 ) t=0:pi/100:6*pi;plot(t.*sin(t),t.*cos(t)2. ( 1)x1=linspace(0,1,100);y1=2*;t=linspace(0,pi,100);x=sin(3*t).*cos(t);y=sin(3*t).*sin(t);plot(x1,y1,r-,x,y,b:);text,1,

5、y=);text,x=sin(3t)cos(t);text,y=sin(3t)sin(t);2)subplot(1,2,1);scatter(x1,y1,10)title(y=);subplot(1,2,2);scatter(x,y,10)3.subplot(1,21);x=1:1:100; y=sin(1./x); plot(x,y)subplot(1,2,2);fplot(sin(1/x),1,100)4.subplot(2,2,1);bar(t,y);subplot(2,2,2);stairs(t,y); subplot(2,2,3);stem(t,y)subplot(2,2,4); s

6、emilogy(t,y);5.theta=linspace(-pi,pi,100);ro=5.*cos(theta)+4; polar(theta,ro);fi=linspace(0,2*pi,100);a=1 r=a.*(1+cos(fi);polar(fi,r);6.t=0:pi/20:2*pi;x=exp(-t./20).*cos(t);y=exp(-t./20).*sin(t);z=t; plot3(x,y,z);t=0:1; x=t;y=t.2;z=t.3; plot3(x,y,z);7. x=-30:0;y=0:30;x,y=meshgrid(x,y);z=10.*sin(sqrt

7、(x.2+y.2)./sqrt(1+x.2+y.2); meshc(x,y,z);8. x=linspace(-3,3,100);y=linspace(-3,3,100);x y=meshgrid(x,y); fxy=-5./(1+x.2+y.2); i=find(abs(x)= & abs(y)/size(A)2.h=466,715,950,1422,1635;w=,;hh=500,900,1500; ww=interp1(h,w,hh,spline) 3.y=log(x);f=polyfit(x,y,5);yy=polyval(f,x);plot(x,y,r-,x,yy,g.)4.N=64

8、;%采樣點數(shù)T=5;%采樣時間終點t=linspace(0,T,N);%給出 N個采樣時間 ti(I=1:N)x=3*exp(-t); %求各采樣點樣本值 xdt=t(2)-t(1);%采樣周期f=1/dt;%采樣頻率 (Hz)X=fft(x);%計算 x的快速傅立葉變換F=X(1:N/2+1);% F(k)=X(k)(k=1:N/2+1)f=f*(0:N/2)/N;%使頻率軸 f 從零開始plot(f,abs(F),-*)%繪制振幅 - 頻率圖x=linspace(1,10,50);Xxlabel(Frequency);ylabel(|F(k)|)5.1) p1=1 2 0 0 7;p2=1

9、 -2;p3=1 0 0 5 1; p12=conv(p1,p2);p=p12+zeros(1,size(p12,2)-size(p3,2),p3; roots(p)(2)A=-1,4,3;2,1,5;0,5,6; Px=polyval(p,A) Pxm=polyvalm(p,A)6.( 1) z=fzero(3*x-sin(x)+1,0)(2) 建立函數(shù)文件 function F=myfun(X) x=X(1);y=X(2); F(1)=x*x+y*y-9;F(2)=x+y-1; 在命令窗口中輸入以下命令： x=fsolve(myfun,3,0,optimset(Display,off) 第

10、6章一、思考題2.fx=inline(1./(1+x.2); I,n=quad(fx,-100000,100000,1e-3); I,n=quadl(fx,-100000,100000,1e-3); x=-100000:100000;y=1./(1+x.*x); trapz(x,y);3.(1) fx=inline(-2*y+2*x*x+2*x); t,y=ode23(fx,0,1)(2) fx=inline(y-exp(x)*cos(x);t,y=ode23(fx,0,3,1) 二、實驗題1. for x=1:3fx=x,x2,x3;1,2*x,3*x;0,2,6*x;diff(fx)end

11、2.(1) x=0:1; y=x.10+10.x+1./log10(x); dy=diff(y)/;(2) x=0:1; y=log(1+x); dy=diff(y,2)/; plot(x(1:99),dy)3.(1) fx=inline( x.2.*sqrt(2*x.*x+3) ); quad(fx,1,5)(2) fx=inline( x./sin(x).2 ); quad(fx,pi/4,pi/3)(3) fx=inline( abs(cos(x+y) ); dblquad(fx,0,pi,0,pi)(4) syms x y; fx=x*y;int(int(fx,y2,y+2),-1,2

12、) x的積分區(qū)間為【 0， 2】時 fx=inline( x.*y );dblquad(fx,0,2,-1,2)4.x=:;y=,; trapz(x,y) 5.(1)yp=inline( -+sin(10*x)*y );t,y=ode23(yp,0,5,1);（2）令 x1y,x2 y ,x3 y ，則可寫出原方程的狀態(tài)方程形式x1x2x2x3cos2t 1x3cost5 2 x3 x2x1(t 1) 3 sintx1010x10-x2001x2015cos2tx312x3cost3 sint(t 1)2建立函數(shù)文件function y=ztfun(t,x)b=0;0;cos(t);y=0,1

13、,0;0,0,1;-1/(3+sin(t),-1,5*cos(2*t)/(t+1)2*x+b; 解微分方程組t,y=ode23(ztfun,0,5,1;0;2);6.建立函數(shù)文件function yy=ztfun(t,y) yy=y(2)*y(3);-y(1)*y(3);*y(1)*y(2);解微分方程組 t,y=ode23(ztfun,0,5,0;1;1) 第7章、思考題3.(1)數(shù)值積分 fx=inline(exp(x).*(1+exp(x).2); quad(fx,0,log(2) 符號積分f=sym(exp(x)*(1+exp(x)2); v=int(f,0,log(2);eval(v

14、)(2)略二、實驗題1.A=sym(1,2,3;x,y,z;3,2,1) rank(A) inv(A) det(A)2.(1) y=sym(sqrt(x+sqrt(x+sqrt(x); y1=diff(y) y2=diff(y,x,2)(2) syms x y; fxy=sin(x2*y)*exp(-x2-y); diff(diff(fxy,x),y)3.(1) syms x int(1/(1+x4)(2) syms x t int(-2*x*x+1)/(2*x*x-3*x+1)2,x,cos(t),exp(2*t)4.syms n x symsum(1/(2*n+1)/(2*x+1)(2*n+1),n,0,inf) symsum(1/(2*n+1)/(2*x+1)(2*n+1),n,0,5)5.(1) syms x taylor(exp(x)+exp(-x)/2,5,0)(2) syms a x taylor(exp(-5*x)*sin(3*x+pi/3),5,a)6.(1)x=solve(sym(x3+a*x+1=0)(2)x y=solve(sqrt(x2+y2)-100=0,3*x+5*y-8=0)y y17. 方程轉(zhuǎn)化為：