(P,xP) ∑x|P(x)∑x(x1-3)30 (P,P)∑IP(x ) i=0 P(x)=(r-b)P(x)-Cip(x) 3)(x-3)-2=x2-6x+7 (2)求S(x)的待定系数: as(f,P)∑fP(x)23=62 (P,P) ∑IP(x)∑1 asGf,P)_h(x)∑f(x,-3)125:125 (P,P)∑IP(x,)∑(x2-3) (f,P2) fP(x)∑∫(x2-6x1+7) 0.5 d2(P2,P2)∑IP(x)∑(x2-6x+7)2140.0357 于是,所求拟合多项式为 y=S,(x)=a P(x)+a,P(x)+a,P(r) =62+1.25(x-3)+0.0357(x2-6x+7 =2.6999+1.0358x+0.0357x 通常,拟合一组数据的多项式次数n越高,则精度越髙,但是计算量也会越大。对于机 械设计的一般数表,取n≤3即可满足要求。3 10 30 3 3 4 0 2 4 0 2 4 0 2 1 4 0 2 1 1 1 1 1 1 = = − − = = =     = = = = i i i i i i i i i i x x x P x x P x P P P xP b ( ) ( ) [ ( )] [ ( )] ( , ) ( , ) 3 3 2 6 7 2 P2 (x) = (x − b)P1 (x) −C1P0 (x) = (x − )(x − ) − = x − x + (2) 求 S (x) 2 的待定系数： 6 2 5 31 1 4 0 4 0 4 0 2 0 4 0 0 0 0 0 0 . [ ( )] ( ) ( , ) ( , )  = = = = =     = = = = i i i i i i i i f P x f P x P P f P 1 25 10 12 5 3 3 4 0 2 4 0 4 0 2 1 4 0 1 1 1 1 1 . . ( ) ( ) [ ( )] ( ) ( , ) ( , ) = = − −  = = =     = = = = i i i i i i i i i i x f x P x f P x P P f P 0 0357 14 0 5 6 7 6 7 4 0 2 2 4 0 4 0 2 2 4 0 2 2 2 2 2 . . ( ) ( ) [ ( )] ( ) ( , ) ( , ) = = − + − +  = = =     = = = = i i i i i i i i i i i i x x f x x P x f P x P P f P 于是，所求拟合多项式为 2 2 2 0 0 1 1 3 3 2 6999 1 0358 0 0357 6 2 1 25 3 0 0357 6 7 x x x x x y S x P x P x P x . . . . . ( ) . ( ) ( ) ( ) ( ) ( ) = + + = + − + − + = =  +  +  通常，拟合一组数据的多项式次数 n 越高，则精度越高，但是计算量也会越大。对于机 械设计的一般数表，取 n  3 即可满足要求