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1、matlab教程(R2010a)课后习题答案第二章 %分段函数的写法syms y xz=int(x*y,x,0,1);g = evalin(symengine, piecewise(y 1/2, char(z) , y = 1/2, 1)G=int(g,y)g = piecewise(1/2 y, y/2, y = 1/2, 1) G = piecewise(1/2 y, y2/4, y 0.5)subindex_A=sub2ind(size(A),I1,J1)subindex_A=find(A0.5)I,J=ind2sub(size(A),subindex_A)index_A=I J%122
2、_2rand(twister,0),A=rand(3,5),B=A0.5,C=find(B)ci,cj=ind2sub(size(A),C) %此法太繁Ci,Cj=find(B)%122_5t=linspace(1,10,100) (1) y=1-exp(-0.5.*t).*cos(2.*t),plot(t,y)(2) L=length(t)for k=1:L, yy(k)=1-exp(-0.5*t(k)*cos(2*t(k), end, plot(t,yy)%122_6clear,format long, rand(twister,1),A=rand(3,3),B=diag(diag(A),
3、C=A.*(B)%或C=A-B%或C=triu(A,1)+tril(A,-1)%习题3-3% s=sign(randint(1,1000,123)-.5);% n=sum(s=-1)rand(state,123),s=sign(rand(1,1000)-.5),n=sum(s=-1)%习题3-4clear allA=1 2;3 4B1=A.(0.5), B2=A(0.5),A1=B1.2A2=B22A1-Anorm(A1-A)A1-A2norm(A1-A2)clear allA=sym(1 2;3 4)B1=A.(0.5), B2=A(0.5),A1=simple(B1.2)A2=simple
4、(B22)A1-Avpa(A1-A)A1-A2vpa(A1-A2)%习题3-5t=linspace(1,10,100) %(1)L=length(t)for k=1:L yy(k)=1-exp(-0.5*t(k)*cos(2*t(k) endfigure(1),plot(t,yy)%(2)y=1-exp(-0.5.*t).*cos(2.*t),figure(2),plot(t,y) figure(3),subplot(1,2,1),plot(t,y)subplot(1,2,2),plot(t,yy)%习题3-6clear,format long, rand(twister,1),A=rand(
5、3,3),B=diag(diag(A),C=A.*(B)%或C=A-B%或C=triu(A,1)+tril(A,-1)%习题3-7clear,x=-3*pi:pi/15:3*pi; y=x; X,Y=meshgrid(x,y); % X=ones(size(y)*x;Y=y*ones(size(x);warning off; Z=sin(X).*sin(Y)./X./Y;% (1)“非数”数目m=sum(sum(isnan(Z); %k=Z(isnan(Z);m=length(k)% (2)绘图surf(X,Y,Z); shading interp% (3)“无裂缝”图形的全部指令：x=-3*
6、pi:pi/15:3*pi;y=x;X,Y=meshgrid(x,y); % X=ones(size(y)*x;Y=y*ones(size(x);X=X+(X=0)*eps;Y=Y+(Y=0)*eps;Z=sin(X).*sin(Y)./X./Y;surf(X,Y,Z);shading interp%习题3-8clearfor k=10:-1:1; A=reshape(1:10*k,k,10); Sa(k,:)=sum(A,1);endSa clearfor k=10:-1:1; A=reshape(1:10*k,k,10); if k=1 Sa(k,:)=A; else Sa(k,:)=sum(A); endendSa 第四章%习题4-1clear allload prob_401;diff_y=diff(y)./diff(t);gradient_y=gradient(y)./gradient(t);% plot(t(1:end-1),diff_y,t,gradient_y)figure(1)subplot(1,2
