1、(1)syms n limit(n3+3n)(1/n) ans =3(2)syms nlimit(n+2)(1/2)-2*(n+1)(1/2)+n(1/2),n,inf) 0(3)syms x; limit(x*cot(2*x),x,0) 1/2(4)syms x m;limit(cos(m/x)x,x,inf)1(5)syms x limit(1/x-1/(exp(x)-1),x,1)(exp(1)-2)/(exp(1)-1)(6) limit(x2+x)(1/2)-x,x,inf) 练习2.41. 求下列不定积分,并用diff验证:Clear syms x y y=1/(1+cos(x);
2、 f=int(y,x) f = tan(1/2*x) y=tan(1/2*x); yx=diff(y,x); y1=simple(yx) y1 = 1/2+1/2*tan(1/2*x)2 syms x yy=1/(1+exp(x);f=int(y,x)f = -log(1+exp(x)+log(exp(x)y=-log(1+exp(x)+log(exp(x);yx=diff(y,x);y1=simple(yx)y1 = 1/(1+exp(x)y=x*sin(x)2; f=int(y,x) f =x*(-1/2*cos(x)*sin(x)+1/2*x)-1/4*cos(x)2-1/4*x2 sy
3、ms x y y=x*(-1/2*cos(x)*sin(x)+1/2*x)-1/4*cos(x)2-1/4*x2; y1=simple(yx) y1 =x*sin(x)2(4) y=sec(x)3;1/2/cos(x)2*sin(x)+1/2*log(sec(x)+tan(x)y=1/2/cos(x)2*sin(x)+1/2*log(sec(x)+tan(x);1/cos(x)32. 求下列积分的数值解1)y=int(x(-x),x,0,1)y =int(x(-x),x = 0 . 1)vpa(y,10)1.2912859972)clear y=int(exp(2*x)*cos(x)3,x,
4、cleary=int(1/(2*pi)(1/2)*exp(-x2/2),x,0,1)y = 7186705221432913/36028797018963968*erf(1/2*2(1/2)*2(1/2)*pi(1/0,2*pi)22/65*exp(pi)4-22/65vpa(ans,10)(3) syms x y=int(1/(2*pi)(1/2)*exp(-x2/2),0,1); vpa(y,14).341344746068552(4) y=int(x*log(x4)*asin(1/x2),1,3);Warning: Explicit integral could not be found
5、. In sym.int at 582.4597721282375 2(5) y=int(1/(2*pi)(1/2)*exp(-x2/2),-inf,inf);.99999999999999 练习2.51判断下列级数的收敛性,若收敛,求出其收敛值。1)syms ns1=symsum(1/n(2n),n,1,inf)s1 = sum(1/(n(2n),n = 1 . Inf)vpa(s1,10)ans = 1.062652416因此不收敛2)syms ns1=symsum(sin(1/n),n,1,inf) s1 =sum(sin(1/n),n = 1 . Inf)vpa(s1,10) 不收敛(
6、3) syms n s=symsum(log(n)/n3,n,1,inf)s =-zeta(1,3)收敛(4) syms n s1=symsum(1/(log10(n)n,n,3,inf)sum(1/(log(n)/log(10)n),n = 3 . inf)(5) syms ns1=symsum(1/n*log10(n),n,2,inf)sum(1/n*log(n)/log(10),n = 2 . Inf)(6) s=symsum(-1)n*n/n2+1,n,1,inf)sum(-1)n/n+1,n = 1 . Inf) 习题3.11)clear;x,y=meshgrid(-30:0.3:3
7、0);z=10*sin(sqrt(x.2+y.2)./sqrt(1+x.2+y.2); meshc(x,y,z) x,y=meshgrid(-30: z=10*sin(x2+y2)(1/2)/(1+x2+y2)(1/2)mesh(x,y,z)1.2.取适当的参数绘制下列曲面的图形。 a=-2:2; b=-3:3; x,y=meshgrid(a,b); z=(1-(x.2)/4-(y.2)/9).(1/2); mesh(x,y,z) hold onmesh(x,y,-z) a=-1:1; b=-2:x,y=meshgrid(a,b); z=(4/9)*(x.2)+(y.2); x,y=meshg
8、rid(-1:1); z=(1/3)*(x.2)-(1/3)*(y.2); 习题3.2P49/例3.2.1命令: limit(limit(x2+y2)/(sin(x)+cos(y),0),pi),-pi2 limit(limit(1-cos(x2+y2)/(x2+y2),0),0),P49/例3.2.2clear;syms x y z dx dy dz zxz zy zxx zxyz=atan(x2*y) z =atan(x2*y) zx=diff(z,x),zy=diff(z,y)zx 2*x*y/(1+x4*y2)zy =x2/(1+x4*y2) dz=zx*dx+zy*dy,dz =2*
9、x*y/(1+x4*y2)*dx+x2/(1+x4*y2)*dzxx=diff(zx,x),zxy=diff(zx,y)zxx =2*y/(1+x4*y2)-8*x4*y3/(1+x4*y2)2zxy =2*x/(1+x4*y2)-4*x5*y2/(1+x4*y2)23.2.1作图表示函数z=x*exp(-x2-y2) (-1x1,0y2)沿x轴方向梯度 b=0: z=x.*exp(-x.2-y.2); px,py=gradient(z,0.1,0.1);contour(a,b,z),hold on, quiver(a,b,px,py),hold off 习题3.41. 解下列微分方程(1)y
10、=dsolve(Dy=x+y,y(0)=1x-x-1+2*exp(x)x=1 2 3x = 1 2 3 -x-1+2*exp(x)3.4366 11.7781 36.1711(2)x=2*x+3*y,y=2*x+y,x(0)=-2,y(0)=2.8,0t10,做相平面图新建M函数function dy=weifen1(t,y)dy=zeros(2,1);dy(1)=2*y(1)+3*y(2);dy(2)=2*y(1)+y(2);输入命令10; t,y=ode15s(weifen1,0,10,-2 2.8); plot(t,y)(3)y-0.01(y)2+2*y1=sin(t),y(0)=0,y
11、(0)=1,0 p=1 0 1;q=1 0 0 0 1;a,b,r=residue(p,q)a = -0.0000 - 0.3536i -0.0000 + 0.3536i 0.0000 - 0.3536i 0.0000 + 0.3536ib = -0.7071 + 0.7071i -0.7071 - 0.7071i 0.7071 + 0.7071i 0.7071 - 0.7071i r = format rat a -1/6369051672525780 - 1189/3363i -1/6369051672525779 + 1189/3363i 1/5095241338020627 - 118
12、9/3363i 1/5095241338020627 + 1189/3363i4.1.5(2) p=1; q=1 0 0 0 1; a,b,r=residue(p,q) 0.1768 - 0.1768i 0.1768 + 0.1768i -0.1768 - 0.1768i -0.1768 + 0.1768ir = a 1189/6726 - 1189/6726i 1189/6726 + 1189/6726i -1189/6726 - 1189/6726i -1189/6726 + 1189/6726i 习题4.24.2.1(1) D=2 1 3 1;3 -1 2 1;1 2 3 2;5 0 6
13、 2; det(D) 6 4.3.3(1) A=0 1 0;1 0 0;0 0 1; B=1 0 0;0 0 1;0 1 0; C=1 -4 3;2 0 -1;1 -2 0; X=C*inv(A)*inv(B)X = -4 3 1 0 -1 2 -2 0 1 习题4.34.3.3(2) D=1 2 3;2 2 3;3 5 1; D1=1 2 3; D2=1 1 3;3 3 1; D3=1 2 1;2 2 2;3 5 3;X1=det(D1)/det(D);X2=det(D2)/det(D);X3=det(D3)/det(D); X1,X2,X3X1 = 1 X2 = 0 X3 =4.4.1(1
14、) A=4 2 -1;3 -1 2;11 3 0; B=4 2 -1 2;3 -1 2 10;11 3 0 8; rank(A),RANK(B) 2 Function call RANK invokes inexact match E:toolboxmatlabmatfunrank.m. 3 习题4.44.4.1(3) A=1 1 1 1;1 2 -1 4;2 -3 -1 -5;3 1 2 11; B=1 1 1 1 5;1 2 -1 4 -2;2 -3 -1 -5 -2;3 1 2 11 0; rank(A),rank(B) 4 习题4.54.5.1(3) A=4 1 -1;3 2 -6;1
15、 -5 3; a,b=eig(A) 92/4963 -1237/1373 -424/1383 -627/815 -449/3622 -1301/1795 -1122/1757 -1097/2638 559/906 -4695/1538 0 0 0 1963/534 0 0 0 8318/993 4.5.1(5) A=5 7 6 5;7 10 8 7;6 8 10 9;5 7 9 10; 431/519 308/3301 472/1191 551/1449 -641/1278 -2209/7323 1175/1911 2100/3973 -434/2081 1050/1381 -855/3148
16、 494/895 368/2975 -1049/1848 -3157/5048 473/908 23/2266 0 0 0 0 1639/1944 0 0 0 0 3615/937 0 0 0 0 2938/97 4.5.3 A=2 0 0;0 3 2;0 2 3; a,b=eig(A); 0 1 0 -985/1393 0 985/1393 985/1393 0 985/1393 1 0 0 0 2 0 0 0 5 p=orth(a)p = 0 -1 0 B=p*A*pB = 1 0 0 p*p 1 0 0 0 0 1 习题5.75.7.5 x=0:0.01: y=exp(-x.2/2);
17、plot(x,y); syms x; vpa(int(exp(-x.2/2),x,0,1),6).855620 n=10000; x=rand(n,1); y=rand(n,1); m=sum(y=60 x4+x5+x6=100 x1+x4=45 x2+x5=75 x3+x6=40 c=10;5;6;4;8;15; A=-1 -1 -1 0 0 0;0 0 0 -1 -1 -1; b=-60;-100; Aeq=1 0 0 1 0 0;0 1 0 0 1 0;0 0 1 0 0 1; beq=45;75;40; lb=zeros(6,1); x,fv=linprog(c,A,b,Aeq,beq,lb)Optimization terminated.x = 0.0000 20.0000 40.0000 45.0000 55.00000.0000fv = 960.0000
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