Matlab之用牛顿均差求插值多项式

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% page 151  3
+ L# A0 F8 Y; T( J6 _3 K  y4 U# L% 写出一个插值多项式
4 G4 z) y; X6 e$ x2 E% input :vector(x,y),interpolation point x0
& U  ?1 V$ Z2 [$ c% output:the result at x = x0
function y0 = page_157_1(x ,y,x0)
+ U2 O* q! U6 n" Nformat long
+ e+ B9 w* |9 ^/ F! ~5 x2 x6 G% a, Ln = length(x);
for j = 1:n     %fill in y colum of Newton triangle
/ |7 F2 `7 f" n$ O    v(j,1) = y(j);
end
for i = 2:n             %for colum i
    for j = 1:n+1-i             %fill in colum from top to bottom
        v(j,i) = (v(j+1,i-1) - v(j,i-1))/(x(j+i-1)-x(j));
    end
end
for i = 1:n
; Q" |# p- f9 r) U    v(i) = v(1,i);     %read along top of triangle      
end     %output coefficients
y0 = v(n)*(x0 - x(n-1)) + v(n-1);  %initial nest
- O; }- C; ^5 ~1 i3 ^  R0 B7 ~* i1 jfor i = 1:n-2                          %use nest
" n% s/ e8 i# n    y0 = y0*(x0 - x(n-1-i)) + v(n-1-i);
$ x! U( D9 }, Q9 p2 Tend

youOK

Matlab之用牛顿均差求插值多项式