《运用matlab建立三次样条插值函数》由会员分享，可在线阅读，更多相关《运用matlab建立三次样条插值函数（2页珍藏版）》请在金锄头文库上搜索。
1、(1)编写三条样条插值函数程序如下：x=149162536496481;y=123456789;n=length(x);lamda(1)=1;miu(n)=1;h=diff(x);df=diff(y)./diff(x);d(1)=6*(df(1)-1/2)/h(1);d(n)=6*(0.5*81A-0.5-df(n-1)/h(n-1);forj=2:n-1lamda(j)=h(j)/(h(j-1)+h(j);miu(j)=h(j-1)/(h(j-1)+h(j);d(j)=6*(df(j)-df(j-1)/(h(j-1)+h(j);endmiu=miu(2:end);u=diag(miu,-1)
2、;r=diag(lamda,1);a=diag(2*ones(1,n);A=u+r+a;%求出矩阵形式的线性方程组M=inv(A)*d;%求岀Mlsymsgforj=1:n-1s(j)=M(j)*(xa+1)-g)A3/(6*h(j)+M(j+1)*(g-xa)A3/(6*h(j)+(ya)-M(j)*h(j)A2/6)*(x(j+1)-g)/ha)+(y(j+1)-M(j+1)*ha)A2/6)*(g-xa)/h(j)；endformatratforj=1:n-1S(j,:)=sym2poly(s(j);%三条样条插值函数end%生成三次样条插值函数图象forj=1:n-1x1=x(j):0
3、.01:x(j+1);y1=polyval(S(j,:),x1);plot(x1,y1,x,y,o);title(spline三次样条插值函数图象);xlabel(x);ylabel(y);gridon;holdon;end得到关于S的矩阵如下:S=0.007814-0.102440.6814410.4131870.000254-0.011720.3185320.8970650.000154-0.009010.2941980.9700692.35E-05-0.002760.1942161.5033061.36E-05-0.002020.175551.6588554.89E-06-0.001080.1417322.0646642.65E-06-0.000750.1256262.3277431.37E-06-0.00050.1099062.663102得到图象如下:spline三次样条插值函数图像
