1、fplot方法 y=x2*sin(x2-x-2); fplot(y,-2 2)(ii)参数方法 t=linspace(0,2*pi,100); x=2*cos(t);y=3*sin(t);(iii) x=-3:0.1:3;y=x; x,y=meshgrid(x,y); z=x.2+y.2; surf(x,y,z)(iv)y=-3:13; z=x.4+3*x.2+y.2-2*x-2*y-2*x.2.*y+6;(v) t=0: x=sin(t);y=cos(t);z=cos(2*t); plot3(x,y,z)(vi) theta=linspace(0,2*pi,50);fai=linspace(
2、0,pi/2,20); theta,fai=meshgrid(theta,fai); x=2*sin(fai).*cos(theta);y=2*sin(fai).*sin(theta);z=2*cos(fai);(vii) x=linspace(0,pi,100); y1=sin(x);y2=sin(x).*sin(10*x);y3=-sin(x); plot(x,y1,x,y2,x,y3)实验5程序exa_5function z=exa_5(x,y)% the size of x and y must be same.z=zeros(size(x);x1,y1=find(x+y1);z(x1
3、,y1)=0.5457*exp(-0.75*y(x1,y1).2-3.75*x(x1,y1).2-1.5*x(x1,y1);x2,y2=find(x+y-1);z(x2,y2)=0.7575*exp(-y(x2,y2).2-6*x(x2,y2).2);x3,y3=find(x+y=-1);z(x3,y3)=0.5457*exp(-0.75*y(x3,y3).2-3.75*x(x3,y3).2+1.5*x(x3,y3); z=exa_5(x,y);实验6查询trapz的功能和用法help trapz查找trapz.m文件所在目录which trapz查看trapz.m程序结构type trapz
4、查看trapz.m文件所在目录还有哪些文件 cd c:MATLAB6p5toolboxmatlabdatafun dir附录b上机实验题实验1 syms theta fai y=sin(fai)*cos(theta)-cos(fai)*sin(theta); simple(y)ans =sin(fai-theta) syms x; f=x4-5*x3+5*x2+5*x-6; factor(f)ans = (x-1)*(x-2)*(x-3)*(x+1) syms a A=1 2; 2 a在命令行中运行(求逆) inv(A)ans = a/(a-4), -2/(a-4) -2/(a-4), 1/(
5、a-4)在命令行中运行(求特征值) eig(A) 1/2+1/2*a+1/2*(17-2*a+a2)(1/2) 1/2+1/2*a-1/2*(17-2*a+a2)(1/2)(1) syms k n symsum(k2,k,1,n)ans =1/3*(n+1)3-1/2*(n+1)2+1/6*n+1/6(2) syms k symsum(1/k2,k,1,inf)ans = 1/6*pi2(3) syms x n symsum(1/(2*n+1)/(2*x+1)(2*n+1),n,0,inf) simple(ans) (化简)ans=1/2*log(2*x+1)2)(1/2)+1)/(2*x+1
6、)2)(1/2)-1) syms x y z f=sin(x2*y*z); s=diff(diff(f,x,2),y); s=subs(s,x,1); s=subs(s,y,1); s=subs(s,z,3)s = 88.2784 syms x taylor(exp(x),9) taylor(log(1+x),9) taylor(sin(x),9)(4) taylor(tan(x),9)实验7 syms y int(exp(2*y)/(exp(y)+2) diff(ans) %验证 simple(ans) %化简 syms x a f=x2/sqrt(a2-x2); int(f,x) simp
7、le(diff(ans) %验证 syms a b x f=1/x/(sqrt(log(x)+a)+sqrt(log(x)+b);实验8 见各章的上机答案实验9程序exb_9_11.ms=1;for n=2:100 s=s*n;s tic;exb_9_11;tocs = 9.3326e+157elapsed_time = 0程序exb_9_12.ma=sym(1:100);s=prod(a);exb_9_12;s = 93326elapsed_time = 0.2500 %可用double(s)转化为数值型符号运算程序788657 %其375位数数值计算的运算结果为Inf第一章上机实验题程序e
8、x1_1.ms=0;for n=1:1000 s=0.1+s;s=s-100 ex1_1s = -1.4069e-012不稳定算法程序ex1_2_1a=zeros(1,21);a(1)=1-1/exp(1);21 a(n)=1-(n-1)*a(n-1);a ex1_2_10.6321 0.3679 0.2642 0.2073 0.1709 0.1455 0.1268 0.1124 0.1009 0.09160.0839 0.0774 0.0718 0.0669 0.0627 0.0590 0.0555 0.0572 -0.0295 1.5596-30.1924稳定算法程序ex1_2_2%ex1
9、_2_2.ma(21)=0.5*(1/exp(1)+1)/21;for n=20:-1:1 a(n)=(1-a(n+1)/n; ex1_2_20.0839 0.0774 0.0718 0.0669 0.0627 0.0590 0.0557 0.0528 0.0501 0.04840.0326 a=1.3611 0.7500 0.52500.7500 0.4360 0.30000.5250 0.3000 0.2136; b=2.6361;1.4736;1.0386; ab 1.1788 -0.0006 1.9658程序ex1_3function y=ex1_4(p,x)np=length(p);
10、y=zeros(size(x);np y=x.*y+p(n); p=1 0 3 0 -2 6; x=1.1 1.2 1.3; ex1_4(p,x)9.4035 11.2723 13.7039可用命令polyval(p,x)进行检验第二章上机实验题 a=4 1 -1;3 2 -6;1 -5 3; b=9;-2;1; det(a)定解方程组唯一解 a=4 -3 3;b=-1 -2 1 a=4 1;3 2;1 -5;b=1 1 1 rank(a) rank(a b)矛盾方程组最小二乘解 a=2 1 -1 1;1 2 1 -1;1 1 2 1; b=1 2 3 null(a)不定解方程组无穷多解 de
11、t(a) %计算行列式 inv(a) %计算逆 v d=eig(a) %计算特征值及特征向量 norm(a,1) norm(a,2) norm(a,inf) %计算各种常用范数 cond(a,1) cond(a,2) cond(a,inf) %计算各种常用条件数与(1)类似程序ex2_2_4.mfunction a=ex2_2_4(n)a=zeros(n);a(1,1 2)=5 6;n-1a(i,i-1 i i+1)=1 5 6;a(n,n-1 n)=1 5;命令 a=ex2_2_4(5) a=ex2_2_4(50) a=ex2_2_4(500) l,u,p=lu(a); inv(p)*l*u
12、 eig(a)不是正定矩阵 a=4 3 1;3 3 -5; a=5 7 6 5;7 10 8 7;6 8 10 9;5 7 9 10; r=chol(a); r*r正定矩阵不是对称矩阵 a=hilb(12); cond(a) inv(a)程序ex2_7.ma=1 1 -1; 1 2 -2; -2 1 1; b=1 0 1l,u=nalu(a);x=ex2_7l(l,b);x=ex2_7u(u,x)程序ex2_7l.mfunction x=ex2_7l(l,b)n=length(b);x=zeros(n,1);x(1)=b(1)/l(1,1);for k=2: x(k)=(b(k)-l(k,1:
13、k-1)*x(1:k-1)/l(k,k);程序ex2_7u.mfunction x=ex2_7u(u,b)x(n)=b(n)/u(n,n);for k=(n-1): x(k)=(b(k)-u(k,k+1:n)*x(k+1:n)/u(k,k);实验8 a=0.3e-15 59.14 3 1;5.291 -6.13 -1 2;11.2 9 5 2;1 2 1 1; b=59.17 46.78 1 2 x=nagauss(a,b) x=nagauss2(a,b)1.2;a2,b2=ex2_9_1(x);cond(a2)1.5;a5,b5=ex2_9_1(x);cond(a5)1.8;a8,b8=ex
14、2_9_1(x);cond(a8)程序ex2_9_1.mfunction a,b=ex2_9_1(x)n=length(x)-1;x=x(:a=ones(n+1,n+1);for k=1: a(:,k+1)=x.k;b=sum(a) a5(6,6)=a5(6,6)+1e-4; a5b5实验10 a,b=ex2_10_1(300); x=nagauss2(a,b,1),toc程序ex2_10_1.mfunction a,b=ex2_10_1(n)a(1,1 2)=2 1; a(k,k-1:k+1)=1 2 1;a(n,n-1,n)=1 2; tic,x=ex2_10_2(a,b);程序ex2_1
15、0_2.mfunction x=ex2_10_2(a,b) a(k,k)=a(k,k)-a(k,k-1)/a(k-1,k-1)*a(k-1,k); b(k)=b(k)-a(k,k-1)/a(k-1,k-1)*b(k-1);x(n)=b(n)/a(n,n);for k=n-1: x(k)=(b(k)-a(k,k+1)*x(k+1)/a(k,k); x=ab, toc第三章上机实验题 p=1 1 1; x=roots(p) polyval(p,x) p=3 0 -4 0 2 -1; p=zeros(1,24); p(1,3)=-5;p(1,7)=8;p(1,8)=-6;p(1,24)=5; p=p
16、(:,24: x=roots(p);寻找有根区间或初始值 f=inline(x*log(sqrt(x2-1)+x)-sqrt(x2-1)-0.5*x fplot(f,1,10); grid on有根区间为1.5 2.5; 初始值为2二分法 x=nabisect(f,1.5,2.5)x = 2.1155Newton迭代法 df=inline(log(x2-1)(1/2)+x)-0.5 x=nanewton(f,df,2)x4-2x fplot(f,-2 2),grid on fzero(f,-0.8),fzero(f,1.2)结果ans = -0.8613 1.23969*x(1)2+36*x(
17、2)2+4*x(3)2-36,x(1)2-2*x(2)2-20*x(3),16*x(1)-x(1)3-2*x(2)2-16*x(3)2,x x,y,h=fsolve(f,0 0 0)x = 0.1342 0.9972 -0.0985 clear x1=sqrt(5)*cos(t)+2;y1=sqrt(5)*sin(t)+3-2*x1; x2=sqrt(2)*cos(t)+3; y2=6*sin(t); plot(x1,y1,x2,y2)图形显示结果(x(1)-2)2+(x(2)-3+2*x(1)2-5,2*(x(1)-3)2+(x(2)/3)2-4 x,y,h=fsolve(f,1.7 -2.
18、8) x,y,h=fsolve(f,3.5 -5.8) x,y,h=fsolve(f,4 -4) x,y,h=fsolve(f,1.6 2)1.7362 -2.69293.4829 -5.63944.0287 -4.11711.6581 1.8936程序ex3_6.mfunction x=ex3_6(fname,x0,x1,eps,n)if nargineps & kN x0=x; x=g*x0+f;if k=N warning(too many times a=5 2 1;-1 3 2;2 -3 4;b=-12 17 -9 ex3_7(a,b,0 0 0,0.5*1e-2)ans = -4.0010 2.9965 2.0014程序ex3_8.mfunction a,b=ex3_8(n)a(1,1:3)=3 -1/2 -1/4;a(2,1:4)=-1/2 3 -1/2 -1/4;a(n-1,n-3:n)=-1/4 -1/2 3 -1/2;a(n,n-2:n)=-1/4 -1/2 3;n-2 a(i,i-2:i+2)=-1/4 -1/2 3 -1/2 -1/4; a,b=ex3_8(100);na
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