数值分析各种代码

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1、追赶法functionx=tridiagsolver(a,b)[n,n]=size(a);fori=1:nifi==1l(i)=a(i,i);y(i)=b(i)/l(i);elsel(i)=a(i,i)-a(i,i-1)*u(i-1);y(i)=(b(i)-y(i-1)*a(i,i-1))/l(i);endifi

2、);m=length(xh);yh=zeros(1,m);c1=ones(n-1,1);c2=ones(1,m);fori=1:nxp=x([1:i-1i+1:n]);yh=yh+y(i)*prod((c1*xh-xp'*c2)./(x(i)-xp'*c2));end线性x=[x1,x2]y=[y1.y2]xh=[xh]抛物线X=[x1,x2,x3]y=[y1，y2，y3]xh=[xh]牛顿差商（输入x,y为列向量）function[p,q]=chashang(x,y)n=length(x);p(:,1)=x;p(:,2)=y;forj=3

3、:n+1p(1:n+2-j,j)=diff(p(1:n+3-j,j-1))./(x(j-1:n)-x(1:n+2-j));endq=p(1,2:n+1)';三次样条x=[0123];y=[0.200.52.01.5-1];pp=csape(x,y,'complete')[breaks,coefs,npolys,ncoefs,dim]=unmkpp(pp)最小二乘x=[0.240.650.951.241.732.012.232.522.772.99]';y=[0.23-0.26-1.1-0.450.270.1-0.290.240.561]';

4、A=[log(x)cos(x)exp(x)];Z=Ay;a0=Z(1)a1=Z(2)a2=Z(3)x=[00.250.500.751.00];y=[1.001.2841.64872.11702.7183];p=polyfit(x,y,2)a2=p(1)a1=p(2)a0=p(3)复合中点functionI=fmid(fun,a,b,n)h=(b-a)/n;x=linspace(a+h/2,b-h/2,n);y=feval(fun,x);I=h*sum(y);复合梯形functionI=ftrapz(fun,a,b,n)h=(b-a)/n;

5、x=linspace(a,b,n+1);y=feval(fun,x);I=h*(0.5*y(1)+0.5*y(n+1)+sum(y(2:n)));复合辛普森functionI=fsimpson(fun,a,b,n)h=(b-a)/n;x=linspace(a,b,2*n+1);y=feval(fun,x);I=h/6*(y(1)+y(2*n+1)+2*sum(y(3:2:2*n-1))+4*sum(y(2:2:2*n)));雅克比迭代function[x,iter]=jacobi(A,b,tol)D=diag(diag(A));L=D-tr

6、il(A);U=D-triu(A);x=zeros(size(b));foriter=1:500x=D(b+U*x+L*x);error=norm(b-A*x)/norm(b);if(error

7、reak;endendSOR迭代function[x,iter]=SOR(A,b,omega,tol)D=diag(diag(A));L=D-tril(A);U=D-triu(A);x=zeros(size(b));foriter=1:500x=(D-omega*L)(omega*b+(1-omega)*D*x+omega*U*x);error=norm(b-A*x)/norm(b);if(error

8、l)ifnargin<4tol=1e-5;endfa=feval(f,a);fb=feval(f,b);whileabs(a-b)>tolx=(a+b)/2;fx=feval(f