matlab newton插值问题给定[0,1.2]内的被插函数f(x)=cosx,插值点 x=[0 0.4 0.8 1.2], y=[1 0.921061 0.696707 0.362358], 编写Newton插值函数,求xi=[0.45 0.58 0.02]处的函数值yi,绘制f(x) 的图形且标出(xi,yi)不会编写
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![matlab newton插值问题给定[0,1.2]内的被插函数f(x)=cosx,插值点 x=[0 0.4 0.8 1.2], y=[1 0.921061 0.696707 0.362358], 编写Newton插值函数,求xi=[0.45 0.58 0.02]处的函数值yi,绘制f(x) 的图形且标出(xi,yi)不会编写](/uploads/image/z/5430981-21-1.jpg?t=matlab+newton%E6%8F%92%E5%80%BC%E9%97%AE%E9%A2%98%E7%BB%99%E5%AE%9A%5B0%2C1.2%5D%E5%86%85%E7%9A%84%E8%A2%AB%E6%8F%92%E5%87%BD%E6%95%B0f%28x%29%3Dcosx%2C%E6%8F%92%E5%80%BC%E7%82%B9+++x%3D%5B0+0.4+0.8+1.2%5D%2C+y%3D%5B1+0.921061+0.696707+0.362358%5D%2C+++%E7%BC%96%E5%86%99Newton%E6%8F%92%E5%80%BC%E5%87%BD%E6%95%B0%2C%E6%B1%82xi%3D%5B0.45+0.58+0.02%5D%E5%A4%84%E7%9A%84%E5%87%BD%E6%95%B0%E5%80%BCyi%2C%E7%BB%98%E5%88%B6f%28x%29+%E7%9A%84%E5%9B%BE%E5%BD%A2%E4%B8%94%E6%A0%87%E5%87%BA%EF%BC%88xi%2Cyi%29%E4%B8%8D%E4%BC%9A%E7%BC%96%E5%86%99)
matlab newton插值问题给定[0,1.2]内的被插函数f(x)=cosx,插值点 x=[0 0.4 0.8 1.2], y=[1 0.921061 0.696707 0.362358], 编写Newton插值函数,求xi=[0.45 0.58 0.02]处的函数值yi,绘制f(x) 的图形且标出(xi,yi)不会编写
matlab newton插值问题
给定[0,1.2]内的被插函数f(x)=cosx,插值点
x=[0 0.4 0.8 1.2], y=[1 0.921061 0.696707 0.362358],
编写Newton插值函数,求xi=[0.45 0.58 0.02]处的函数值yi,绘制f(x) 的图形且标出(xi,yi)
不会编写
绘制f(x) 的图形且标出(xi,yi)
求帮助啊
matlab newton插值问题给定[0,1.2]内的被插函数f(x)=cosx,插值点 x=[0 0.4 0.8 1.2], y=[1 0.921061 0.696707 0.362358], 编写Newton插值函数,求xi=[0.45 0.58 0.02]处的函数值yi,绘制f(x) 的图形且标出(xi,yi)不会编写
function f = Newton(x,y,x0)
%本程序为Newton插值,其中x,y
%为插值节点和节点上的函数值,输出为插值点x0的函数值,
%x0可以是向量.
syms t;
if(length(x) == length(y))
n = length(x);
c(1:n) = 0.0;
else
disp('x和y的维数不相等!');
return;
end
f = y(1);
y1 = 0;
l = 1;
for(i=1:n-1)
for(j=i+1:n)
y1(j) = (y(j)-y(i))/(x(j)-x(i));
end
c(i) = y1(i+1);
l = l*(t-x(i));
f = f + c(i)*l;
simplify(f);
y = y1;
if(i==n-1)
if(nargin == 3)
f = subs(f,'t',x0);
else
f = collect(f); %将插值多项式展开
f = vpa(f,6);
end
end
end
x=[0 0.4 0.8 1.2];
y=[1 0.921061 0.696707 0.362358];
xi=[0.45 0.58 0.02];
yi = Newton(x,y,xi);
xx=0:0.01:1.2;
plot(xx,cos(xx),xi,yi,'or')