东北大学matlab作业汇总.docx
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东北大学matlab作业汇总
第一部分:
1、安装MATLAB软件,应用demo命令了解主要功能,熟悉基本功能,会用help命令。
2、用MATLAB语句输入矩阵
和
,
前面给出的是
矩阵,如果给出
命令将得出什么结果?
解:
>>A=[1234;4321;2341;3241]
B=[1+4j2+3j3+2j4+1j;4+1j3+2j2+3j1+4j;2+3j3+2j4+1j1+4j;3+2j2+3j4+1j1+4j]
A=
1234
4321
2341
3241
B=
1.0000+4.0000i2.0000+3.0000i3.0000+2.0000i4.0000+1.0000i
4.0000+1.0000i3.0000+2.0000i2.0000+3.0000i1.0000+4.0000i
2.0000+3.0000i3.0000+2.0000i4.0000+1.0000i1.0000+4.0000i
3.0000+2.0000i2.0000+3.0000i4.0000+1.0000i1.0000+4.0000i
>>A(5,6)=5
A=
123400
432100
234100
324100
000005
3、假设已知矩阵
,试给出相应的MATLAB命令,将其全部偶数行提取出来,赋给
矩阵,用
命令生成
矩阵,用上述命令检验一下结果是不是正确。
解:
>>A=magic(8)
A=
642361606757
955541213515016
1747462021434224
4026273736303133
3234352928383925
4123224445191848
4915145253111056
858595462631
>>B=A(2:
2:
end,:
)
B=
955541213515016
4026273736303133
4123224445191848
858595462631
4、用数值方法可以求出
,试不采用循环的形式求出和式的数值解。
由于数值方法是采用double形式进行计算的,难以保证有效位数字,所以结果不一定精确。
试采用运算的方法求该和式的精确值。
解:
>>symsS
>>S=sum(sym
(2).^[0:
63])
S=
184********709551615
5、选择合适的步距绘制出下面的图形。
(1)
,其中
;
(2)
,其中
。
解:
(1)>>t=[-1:
0.001:
1];y=sin(1./t);plot(t,y)
(2)>>t=[-pi:
0.001:
pi];y=sin(tan(t)-tan(sin(t)));plot(t,y)
6、试绘制出二元函数
的三维图和三视图。
解:
>>[x,y]=meshgrid(-2:
.1:
2);z=1./(sqrt((1-x).^2+y.^2))+1./(sqrt((1+x).^2+y.^2));
>>surf(x,y,z),shadingflat
7、试求出如下极限。
(1)
;
(2)
;(3)
。
解:
(1)
>>symsx;f=(3^x+9^x)^(1/x);limit(f,x,inf)
ans=
9
(2)
>>symsxy;f=x*y/((x*y+1)^(0.5)-1);limit(limit(f,x,0),y,0)
ans=
2
(3)
>>symsxy;f=(1-cos(x^2+y^2))/((x^2+y^2)*exp(x^2+y^2));limit(limit(f,x,0),y,0)
ans=
0
8、已知参数方程
,试求出
和
。
解:
>>symst;
x=log(cos(t));
y=cos(t)-t*sin(t);
>>diff(y,t)/diff(x,t)
ans=
(cos(t)*(2*sin(t)+t*cos(t)))/sin(t)
>>f=diff(y,t,2)/diff(x,t,2);subs(f,t,sym(pi/3))
ans=
3/8-(pi*3^(1/2))/24
9、假设
,试求
解:
>>symsxyt
f=int(exp(-t^2),t,0,x*y);
x/y*diff(f,x,2)-2*diff(diff(f,x),y)+diff(f,y,2)
ans=
(2*x^2*y^2)/exp(x^2*y^2)-(2*x^3*y)/exp(x^2*y^2)-2/exp(x^2*y^2)
10、试求出下面的极限。
(1)
;
(2)
。
解:
(1)
>>symskn;limit(symsum(1/((2*k)^2-1),k,1,n),n,inf)
ans=
1/2
(2)
>>symskn
limit(n*symsum(1/(n^2+k*pi),k,1,n),n,inf)
ans=
1
11、试求出以下的曲线积分。
(1)
,
为曲线
,
,
。
(2)
,其中
为
正向上半椭圆。
解:
(1)
>>symsat;x=a*(cos(t)+t*sin(t));y=a*(sin(t)-t*cos(t));
f=x^2+y^2;S=int(f*sqrt(diff(x,t)^2+diff(y,t)^2),t,0,2*pi)
S=
2*pi^2*(2*pi^2+1)*(a^2)^(3/2)
(2)
>>symsat;x=a*(cos(t)+t*sin(t));y=a*(sin(t)-t*cos(t));
f=x^2+y^2;S=int(f*sqrt(diff(x,t)^2+diff(y,t)^2),t,0,2*pi)
S=
2*pi^2*(2*pi^2+1)*(a^2)^(3/2)
>>symsxyabct;x=c*cos(t)/a;y=c*sin(t)/b;
P=y*x^3+exp(y);Q=x*y^3+x*exp(y)-2*y;
ds=[diff(x,t);diff(y,t)];S=int([PQ]*ds,t,0,pi)
S=
-(2*c*(15*b^4-2*c^4))/(15*a*b^4)
12、求出Vandermonde矩阵
的行列式,并以最简的形式显示结果。
解:
>>symsabcde;A=vander([abcde])
A=
[a^4,a^3,a^2,a,1]
[b^4,b^3,b^2,b,1]
[c^4,c^3,c^2,c,1]
[d^4,d^3,d^2,d,1]
[e^4,e^3,e^2,e,1]
>>det(A),simplify(ans)
ans=
a^4*b^3*c^2*d-a^4*b^3*c^2*e-a^4*b^3*c*d^2+a^4*b^3*c*e^2+a^4*b^3*d^2*e-a^4*b^3*d*e^2-a^4*b^2*c^3*d+a^4*b^2*c^3*e+a^4*b^2*c*d^3-a^4*b^2*c*e^3-a^4*b^2*d^3*e+a^4*b^2*d*e^3+a^4*b*c^3*d^2-a^4*b*c^3*e^2-a^4*b*c^2*d^3+a^4*b*c^2*e^3+a^4*b*d^3*e^2-a^4*b*d^2*e^3-a^4*c^3*d^2*e+a^4*c^3*d*e^2+a^4*c^2*d^3*e-a^4*c^2*d*e^3-a^4*c*d^3*e^2+a^4*c*d^2*e^3-a^3*b^4*c^2*d+a^3*b^4*c^2*e+a^3*b^4*c*d^2-a^3*b^4*c*e^2-a^3*b^4*d^2*e+a^3*b^4*d*e^2+a^3*b^2*c^4*d-a^3*b^2*c^4*e-a^3*b^2*c*d^4+a^3*b^2*c*e^4+a^3*b^2*d^4*e-a^3*b^2*d*e^4-a^3*b*c^4*d^2+a^3*b*c^4*e^2+a^3*b*c^2*d^4-a^3*b*c^2*e^4-a^3*b*d^4*e^2+a^3*b*d^2*e^4+a^3*c^4*d^2*e-a^3*c^4*d*e^2-a^3*c^2*d^4*e+a^3*c^2*d*e^4+a^3*c*d^4*e^2-a^3*c*d^2*e^4+a^2*b^4*c^3*d-a^2*b^4*c^3*e-a^2*b^4*c*d^3+a^2*b^4*c*e^3+a^2*b^4*d^3*e-a^2*b^4*d*e^3-a^2*b^3*c^4*d+a^2*b^3*c^4*e+a^2*b^3*c*d^4-a^2*b^3*c*e^4-a^2*b^3*d^4*e+a^2*b^3*d*e^4+a^2*b*c^4*d^3-a^2*b*c^4*e^3-a^2*b*c^3*d^4+a^2*b*c^3*e^4+a^2*b*d^4*e^3-a^2*b*d^3*e^4-a^2*c^4*d^3*e+a^2*c^4*d*e^3+a^2*c^3*d^4*e-a^2*c^3*d*e^4-a^2*c*d^4*e^3+a^2*c*d^3*e^4-a*b^4*c^3*d^2+a*b^4*c^3*e^2+a*b^4*c^2*d^3-a*b^4*c^2*e^3-a*b^4*d^3*e^2+a*b^4*d^2*e^3+a*b^3*c^4*d^2-a*b^3*c^4*e^2-a*b^3*c^2*d^4+a*b^3*c^2*e^4+a*b^3*d^4*e^2-a*b^3*d^2*e^4-a*b^2*c^4*d^3+a*b^2*c^4*e^3+a*b^2*c^3*d^4-a*b^2*c^3*e^4-a*b^2*d^4*e^3+a*b^2*d^3*e^4+a*c^4*d^3*e^2-a*c^4*d^2*e^3-a*c^3*d^4*e^2+a*c^3*d^2*e^4+a*c^2*d^4*e^3-a*c^2*d^3*e^4+b^4*c^3*d^2*e-b^4*c^3*d*e^2-b^4*c^2*d^3*e+b^4*c^2*d*e^3+b^4*c*d^3*e^2-b^4*c*d^2*e^3-b^3*c^4*d^2*e+b^3*c^4*d*e^2+b^3*c^2*d^4*e-b^3*c^2*d*e^4-b^3*c*d^4*e^2+b^3*c*d^2*e^4+b^2*c^4*d^3*e-b^2*c^4*d*e^3-b^2*c^3*d^4*e+b^2*c^3*d*e^4+b^2*c*d^4*e^3-b^2*c*d^3*e^4-b*c^4*d^3*e^2+b*c^4*d^2*e^3+b*c^3*d^4*e^2-b*c^3*d^2*e^4-b*c^2*d^4*e^3+b*c^2*d^3*e^4
ans=
(a-b)*(a-c)*(a-d)*(b-c)*(a-e)*(b-d)*(b-e)*(c-d)*(c-e)*(d-e)
13、试对矩阵
进行Jordan变换,并得出变换矩阵。
解:
>>A=[-2,0.5,-0.5,0.5;0,-1.5,0.5,-0.5;2,0.5,-4.5,0.5;2,1,-2,-2];
>>[VJ]=jordan(sym(A))
V=
[0,1/2,1/2,-1/4]
[0,0,1/2,1]
[1/4,1/2,1/2,-1/4]
[1/4,1/2,1,-1/4]
J=
[-4,0,0,0]
[0,-2,1,0]
[0,0,-2,1]
[0,0,0,-2]
14、试用数值方法和解析方法求取下面的Sylvester方程,并验证得出的结果。
解:
数值方法:
>>A=[3,-6,-4,0,5;1,4,2,-2,4;-6,3,-6,7,3;-13,10,0,-11,0;0,4,0,3,4];
>>B=[3,-2,1;-2,-9,2;-2,-1,9];
>>C=[-2,1,-1;4,1,2;5,-6,1;6,-4,-4;-6,6,-3];
>>X=lyap(A,B,C)
X=
-4.056896419147292-14.5127820773816121.565310728709521
.0355********
9.48864527098846025.932327650327640-4.417733416157587
2.69692229648064621.645009214025027-2.885084137489283
7.72287238941890831.909960533088562-3.763408710201076
>>norm(A*X+X*B+C)
ans=
3.435635978567079e-13
解析方法:
>>X=lyap(sym(A),B,C)
X=
[-434641749950/107136516451,-4664546747350/321409549353,503105815912/321409549353][3809507498/107136516451,8059112319373/321409549353,-880921527508/321409549353][1016580400173/107136516451,8334897743767/321409549353,-1419901706449/321409549353][288938859984/107136516451,6956912657222/321409549353,-927293592476/321409549353][827401644798/107136516451,10256166034813/321409549353,-1209595497577/321409549353]
>>A*X+X*B+C
ans=
[0,0,0]
[0,0,0]
[0,0,0]
[0,0,0]
[0,0,0]
15、假设已知矩阵
如下,试求出
,
,
。
解:
>>A=[-4.5,0,0.5,-1.5;-0.5,-4,0.5,-0.5;1.5,1,-2.5,1.5;0,-1,-1,-3];
>>A=sym(A),symst;expm(A*t)
A=
[-9/2,0,1/2,-3/2]
[-1/2,-4,1/2,-1/2]
[3/2,1,-5/2,3/2]
[0,-1,-1,-3]
ans=
[exp(-3*t)/2+exp(-5*t)/2-(t*exp(-3*t))/2+(t^2*exp(-3*t))/2,exp(-5*t)/2-exp(-3*t)/2+t*exp(-3*t),(t*exp(-3*t))/2+(t^2*exp(-3*t))/2,exp(-5*t)/2-exp(-3*t)/2-(t*exp(-3*t))/2+(t^2*exp(-3*t))/2]
[exp(-5*t)/2-exp(-3*t)/2+(t*exp(-3*t))/2,exp(-3*t)/2+exp(-5*t)/2,(t*exp(-3*t))/2,exp(-5*t)/2-exp(-3*t)/2+(t*exp(-3*t))/2]
[exp(-3*t)/2-exp(-5*t)/2+(t*exp(-3*t))/2,exp(-3*t)/2-exp(-5*t)/2,exp(-3*t)+(t*exp(-3*t))/2,exp(-3*t)/2-exp(-5*t)/2+(t*exp(-3*t))/2]
[-(t^2*exp(-3*t))/2,-t*exp(-3*t),-(t*exp(-3*t)*(t+2))/2,-(exp(-3*t)*(t^2-2))/2]
>>A=sym(A);symst
>>sin(A*t)
ans=
[-sin((9*t)/2),0,sin(t/2),-sin((3*t)/2)]
[-sin(t/2),-sin(4*t),sin(t/2),-sin(t/2)]
[sin((3*t)/2),sin(t),-sin((5*t)/2),sin((3*t)/2)]
[0,-sin(t),-sin(t),-sin(3*t)]
>>A=sym(A);symst
>>expm(A*t)*sin(A^2*expm(A*t)*t)
ans=
[sin(t*((3*exp(-3*t))/2-(25*exp(-5*t))/2+(9*t*exp(-3*t))/2))*((t*exp(-3*t))/2+(t^2*exp(-3*t))/2)+sin(t*((17*exp(-3*t))/2+(25*exp(-5*t))/2-(21*t*exp(-3*t))/2+(9*t^2*exp(-3*t))/2))*(exp(-3*t)/2+exp(-5*t)/2-(t*exp(-3*t))/2+(t^2*exp(-3*t))/2)+sin(t*(exp(-3*t)-6*t*exp(-3*t)+(9*t^2*exp(-3*t))/2))*(exp(-3*t)/2-exp(-5*t)/2+(t*exp(-3*t))/2-(t^2*exp(-3*t))/2)+sin(t*((25*exp(-5*t))/2-(15*exp(-3*t))/2+(9*t*exp(-3*t))/2))*(exp(-5*t)/2-exp(-3*t)/2+t*exp(-3*t)),sin(t*((9*exp(-3*t))/2-(25*exp(-5*t))/2))*((t*exp(-3*t))/2+(t^2*exp(-3*t))/2)+sin(t*((25*exp(-5*t))/2-(21*exp(-3*t))/2+9*t*exp(-3*t)))*(exp(-3*t)/2+exp(-5*t)/2-(t*exp(-3*t))/2+(t^2*exp(-3*t))/2)-sin(t*(6*exp(-3*t)-9*t*exp(-3*t)))*(exp(-3*t)/2-exp(-5*t)/2+(t*exp(-3*t))/2-(t^2*exp(-3*t))/2)+sin(t*((9*exp(-3*t))/2+(25*exp(-5*t))/2))*(exp(-5*t)/2-exp(-3*t)/2+t*exp(-3*t)),sin(t*(6*exp(-3*t)-(13*t*exp(-3*t))/2-(11*t^2*exp(-3*t))/2+(11*t*exp(-3*t)*(t+2))/2))*((t*exp(-3*t))/2+(t^2*exp(-3*t))/2)-sin(t*(3*exp(-3*t)-(19*t*exp(-3*t))/2-(5*t^2*exp(-3*t))/2+(5*t*exp(-3*t)*(t+2))/2))*(exp(-5*t)/2-exp(-3*t)/2+t*exp(-3*t))-sin(t*(5*exp(-3*t)+5*t*exp(-3*t)-(t^2*exp(-3*t))/2-4*t*exp(-3*t)*(t+2)))*(exp(-3*t)/2-exp(-5*t)/2+(t*exp(-3*t))/2-(t^2*exp(-3*t))/2)-sin(t*(2*exp(-3*t)-(21*t*exp(-3*t))/2-(21*t^2*exp(-3*t))/2+6*t*exp(-3*t)*(t+2)))*(exp(-3*t)/2+exp(-5*t)/2-(t*exp(-3*t))/2+(t^2*exp(-3*t))/2),sin(t*((25*exp(-5*t))/2-(25*exp(-3*t))/2+(9*t*exp(-3*t))/2+(5*t^2*exp(-3*t))/2-(5*exp(-3*t)*(t^2-2))/2))*(exp(-5*t)/2-exp(-3*t)/2+t*exp(-3*t))+sin(t*((t^2*exp(-3*t))/2-6*t*exp(-3*t)+4*exp(-3*t)*(t^2-2)))*(exp(-3*t)/2-exp(-5*t)/2+(t*exp(-3*t))/2-(t^2*exp(-3*t))/2)+sin(t*((25*exp(-3*t))/2-(25*exp(-5*t))/2+(9*t*exp(-3*t))/2-(11*t^2*exp(-3*t))/2+(11*exp(-3*t)*(t^2-2))/2))*((t*exp(-3*t))/2+(t^2*exp(-3*t))/2)-sin(t*((25*exp(-3*t))/2-(25*exp(-5*t))/2+(21*t*exp(-3*t))/2-(21*t^2*exp(-3*t))/2+6*exp(-3*t)*(t^2-2)))*(exp(-3*t)/2+exp(-5*t)/2-(t*exp(-3*t))/2+(t^2*exp(-3*t))/2)]
[sin(t*((17*exp(-3*t))/2+(25*exp(-5*t))/2-(21*t*exp(-3