MATLAB例题程序

题P30 1-5

A=[97,67,34,10;-78,75,65,5;32,5,-23,-59;0,-12,54,7]; B=A(1:3,:);

C=A(:,1:2);

D=A(2:4,3:4);

E=B*C;

F=find(A>=50&A<=100)

题P30 2-1

x=-74/180*pi;

y=-27/180*pi;

Sin(x^2+y^2)/(sqrt(tan(abs(x+y)))+pi);

?题P30 2-2

a=-3.0:0.1:3.0;

exp.^(-0.3*a).*sin(a+0.3)

题P30 2-4

A=[3,54,2;34,-45,7;87,90,15];

B=[1,-2,67;2,8,74;9,3,0];

C=A*B

C1=A.*B

D=A^3

D1=A.^3

E=A/D

E1=A./D

F=[A,B]

F1=[A([1,3],:)；B^2]

题P78 2-1.4

t=-2*pi:pi/50:2*pi;

>> x=t.*sin(t);

>> y=t.*cos(t);

>> plot(x,y)

题P78 2-1.3

ezplot('x^2+2*y^2-64')

题P78 2-2.1

t=-2*pi:pi/100:2*pi;

x1=sin(3*t).*cos(t);

y1=sin(3*t).*sin(t);

x2=-1:0.001:1;

y2=2*x2-0.5;

plot(x1,y1,'r:',x2,y2,'g.')

title('x from -2*{\pi } to 2*{\pi}');

xlabel('菊花x');

ylabel('向日葵y');

text(1.5,0.5,'曲线y2=2*x2-0.5');

text(1.5,0.5,'曲线x1=sin(3*t).*cos(t);y1=sin(3*t).*sin(t)'); legend('y1','y2');

题P78 2-6.1

t=0:pi/100:2*pi;

x=exp(-t/20).*cos(t);

x=exp(-t/20).*sin(t);

z=t;

plot3(x,y,z)

题P78 2-6.2

x=t;

y=t.^2;

z=t.^3;

plot3(x,y,z)

题P78 2-7

xx=-30:0.1:0;

yy=0:0.1:30

[X,Y]=meshgrid(xx,yy);

Z=10*sin(sqrt(X.^2+Y.^2))./sqrt(1+X.^2+Y.^2);

meshc(X,Y,Z)

题P78 2-8

xx=-3:0.01:3;

yy=-3:0.01:3;

[X,Y]=meshgrid(xx,yy);

Z=-5./(1+X.^2+Y.^2);

i=find(abs(x)<=0.8 & abs(y)<=0.5);

fxy(i)=NaN;

Mesh(X,Y,Z)

镂空不会？？？

题P104 2-1

A=[1，-1，2，3;0，9，3,3;7，-5，0，2;23，6，8，3];

D=diag(A)%主对角线元素

B=triu(A)%上三角

R=rank(A)%秩

E=trace(A)%迹

NA=[norm(A,1),norm(A,),norm(A,inf)]%范

C1=cond(A)

题P104 3

A=[2,-1,0,0,0;-1,2,-1,0,0;0,-1,2,-1,0;0,0,-1,2,-1;0,0,0,-1,2] b=[1;0;0;0;0]

tic

x2=A\b;

toc

tic

x1=inv(A)*b;

toc

tic

[L,U]=lu(A);

x3=U\(L\b);

toc

x1=x1'

x2=x2'

x3=x3'

题P121 2-2

h=[466,715,950,1422,1635]

t=[ 7.04,4.28,3.40,2.52,2.13]

x=[500,900,1500]

y=interp1(h,t,x,'spline')

题P121 2-3

x=1:1:101;

y=log(x);

f=polyfit(x,y,5)

y1=0.0002*x.^3-0.0103*x.^2+0.2821*x+0.2546;

plot(x,y,'r:',x,y1,'y.')

题P134 2-1

二、实验题

1.

for x=1:3

fx=[x,x^2,x^3;1,2*x,3*x;0,2,6*x];

diff(fx)

end

2.

（1）x=0:0.01:1;

y=x.^10+10.^x+1./log10(x);

dy=diff(y)/0.01;

（2）x=0:0.01:1;

y=log(1+x);

dy=diff(y,2)/0.01;

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,y^2,y+2),-1,2)

x的积分区间为【0，2】时

fx=inline('x.*y');

dblquad(fx,0,2,-1,2)