发布时间 : 星期三 文章MATLAB教程习题答案更新完毕开始阅读
%p172_18
load prob_data418, who,x
P=polyfit(x,y,5), xx=-1:0.01:4, yy=polyval(P,xx), plot(xx,yy,x,y,'*r') legend('拟合曲线','原始曲线','Location','SouthEast') %解法二
x0=x';y0=y';m=length(x);n=5;X=zeros(m,n+1); for k=1:n
X(:,n-k+1)=(x0.^k); end
X(:,n+1)=ones(m,1);aT=(X\\y0)',(P==aT) 第五章 %p213_1 t=2*pi*(0:199)/199; a=4;b=2;x=a*cos(t);y=b*sin(t); plot(x,y,'r.','MarkerSize',15) %p213_2 t = 0:.01:2*pi; P=1-cos(t); polar(t,P), title('P=1-cos\\theta') %p213_3 A=[170,120,180,200,190,220];B=[120,100,110,190,170,180];C=[70,50,80,100,95,120]; bar([A;B;C]','stacked'),legend('A','B','C','Location','NorthWest') %p215_5 t=4*pi*(0:100)/100; x=sin(t);y=cos(t);z=t; plot3(x,y,z,'k','LineWidth',3),box on %p216_6 x=-3:0.1:3;y=x;[X,Y]=meshgrid(x,y);Z=4.*X.*exp(-X.^2-Y.^2);mesh(X,Y,Z) colormap(hot),shading interp,hidden off %p216_7 x=4*pi*(-50:50)/50;y=x;[X,Y]=meshgrid(x,y);Z=sin(X+Y)./(X+Y);surf(X,Y,Z) view([21,32]) %图形界面旋转图形，认为合适后记下方位角和俯视角，再写出命令 shading interp %p216_9 [X,Y,Z]=sphere(40); colormap(jet), surf(X,Y,Z),axis equal off, shading flat,light;lighting flat, view([18,42]),spinmap(5,1) 第六章 %p239_1 %for循环 5 S=0.2;SUM=1; tic for i=0:1000000 SUM=SUM+S; S=S*0.2; end t=toc, SUM %while循环 S=0.2; SUM=1; i=0; tic while i<=1000000 SUM=SUM+S; S=S*0.2; i=i+1; end t=toc, SUM %sym syms i; tic, SUM=vpa(symsum(0.2.^i,0,1000000),6), t=toc %numeral N=1000000; S=zeros(1,N); tic for k=1:N S(k)=0.2.^(k-1); end t=toc, sum(S) %p239_2 function funp239_2(n) %function name: p239_2.m % n The number of sides, while n>=3 % draw circle, while no parameter % input \ if nargin~=0 & (n<0 | fix(n)~=n) disp('input parameter error! Please try again.') else switch nargin case 0 a=100; t=(0:a)/a*2*pi; ss=exp(i*t); plot(real(ss),imag(ss)) axis equal, axis off otherwise if n==1 | n==2,disp('please input n>=3') else t=(0:n)/n*2*pi; 6 ss='exp(i*t)'; se=eval(ss); plot(real(se),imag(se)) axis equal, axis off end end end %p240_3 %p240_3_@(x)(exp)，匿名函数表达式法 y0=@(x)(-exp(-x)*abs(sin(cos(x)))); fplot(y0,[-5,+4]) [x,fval]=fminbnd(hh,-1,1); hold on, plot(x,fval,'*r') %p240_3_function子程序函数句柄法 function y=funp240_3(x) y=-exp(-x)*abs(sin(cos(x))); %main program hh=@funp240_3; fplot(hh,[-5,+4]), [x,fval]=fminbnd(hh,-1,1); hold on, plot(x,fval,'*r') %p240_3_inline内联函数法 y1=inline('-exp(-x)*abs(sin(cos(x)))'); [x,fval]=fminbnd(y1,-1,1) x0=[-5,4]; fplot(y1,x0), hold on, plot(x,fval,'*r') %p240_3_char字符串法 y2='-exp(-x)*abs(sin(cos(x)))'; [x,fval]=fminbnd(y2,-1,1) x0=[-5,4]; ezplot(y2,x0), hold on, plot(x,fval,'*r') %p240_4 cd .. %改变路径 cd toolbox\\matlab\\elmat\\private HH=@smoke smoke(3,0,'double'), HH(3,0,'double') %两种方法均可正确调用 cd .., cd .., cd .., cd .., cd work %回到matlab默认工作路径 HH(4,0,'double'),feval(HH,4,0,'double') %句柄函数可正确调用 smoke(4,0,'double') %因不在当前路径上，用函数名调用出错 第七章 %p263_1.m and p263_1.mdl simulink xFinal %integer values %p263_2.mdl 7 8