现代数值数学和计算习题答案(同济版)(17)

y=atan(x);

%formthedifferencestable

forj=2:n,

y(1:n+1-j,j)=diff(y(1:n+2-j,j-1))/((j-1)*h);end

%newtoncoeff

y=y(1,:);formatlonge

fprintf(’\nthecoefficientsofNewtoninterpolationis:\n\n’);fprintf(’%12.9f’,y);pz=[];

v=linspace(0,8,33);fort=v,

z=y(n);

forj=n-1:-1:1,

z=z*(t-x(j))+y(j);end

pz=[pzz];end

plot(v,pz,’g*-’,v,atan(v),’b+:’);fprintf(’\nxip(xi)atan(xi)error\n’);forj=1:length(v),

fprintf(’%12.6f%12.6f%12.6f%12.6f\n’,...

v(j),pz(j),atan(v(j)),abs(pz(j)-atan(v(j))));

end

[1,6]

arctanx

:

2.

2-16

17