MATLAB课后习题答案
2.1
x=[15 22 33 94 85 77 60]
x(6)
x([1 3 5])
x(4:end)
x(find(x>70))
2.3
A=zeros(2,5);
A(:)=-4:5
L=abs(A)>3
islogical(L)
X=A(L)
2.4
A=[4,15,-45,10,6;56,0,17,-45 ,0]
find(A>=10&A<=20)
2.5
p1=conv([1,0,2],conv([1,4],[ 1,1]));
p2=[1 0 1 1];
[q,r]=deconv(p1,p2);
cq='商多项式为 '; cr='余多项式为 ';
disp([cq,poly2str(q,'s')]),d isp([cr,poly2str(r,'s')])
3.1
n=(-10:10)';
y=abs(n);
plot(n,y,'r.','MarkerSize',2 0)
axis equal
grid on
xlabel('n')
3.2
x=0:pi/100:2*pi;
y=2*exp(-0.5*x).*sin(2*pi*x) ;
plot(x,y),grid on;
3.3
t=0:pi/50:2*pi;
x=8*cos(t);
y=4*sqrt(2)*sin(t);
z=-4*sqrt(2)*sin(t);
plot3(x,y,z,'p');
title('Line in 3-D Space');
text(0,0,0,'origin');
xlabel('X'),ylable('Y'),zlab le('Z');grid;
3.4
theta=0:0.01:2*pi;
rho=sin(2*theta).*cos(2*thet a);
polar(theta,rho,'k');
3.5
[x,y,z]=sphere(20);
z1=z;
z1(:,1:4)=NaN;
c1=ones(size(z1));
surf(3*x,3*y,3*z1,c1);
hold on
z2=z;
c2=2*ones(size(z2));
c2(:,1:4)=3*ones(size(c2(:,1 :4)));
surf(1.5*x,1.5*y,1.5*z2,c2);
colormap([0,1,0;0.5,0,0;1,0, 0]);
grid on
hold off
4.1
for m=100:999
m1=fix(m/100);
m2=rem(fix(m/10),10);
m3=rem(m,10);
if
m==m1*m1*m1+m2*m2*m2+m3*m3*m3 disp(m)
end
end
4.3
y=0;n=100;
for i=1:n
y=y+1/i/i;
end
y
4.4
s=0;
for i=1:5
s=s+factor(i);
end
s
4.5
sum=0;i=1;
while sum<2000
sum=sum+i;
i=i+1;
end;
n=i-2
4.6
i=0;k=0;
while i<=63
k=k+2^i;
i=i+1;
end
k
i
i=0;k=0;
for i=0:63
k=k+2^i;
end
i
k
5.1
A=[2,1,-5,1;1,-5,0,7;0,2,1,-1;1,6,-1,-4];
b=[13,-9,6,0]';
x=A\b
5.3
X=linspace(0,2*pi,50);
Y=sin(X);
P=polyfit(X,Y,3)
AX=linspace(0,2*pi,50);
Y=sin(X);
Y1=polyval(P,X)
plot(X,Y,':O',X,Y1,'-*')