Da thuc niuton

tỉ hiệu cấp1: y[xi,xj] = (yi-yj)/(xi,xj)

ti hieu cap2:y[xi,xj,xk] = (y[xi,xj] - y[xj,xk])/(xi-xk)

Da thuc niuton tien :

Pn(x) = y0 + (x-x0)y[x0,x1] + (x-x0)(x-x1)y[x0,x1,x2] +......+(x-x0)..(x-xn-1)y[x0,..,xn]

Da thuc niuton lui:

Pn(x)=yn+(x-xn)y[xn,xn-1]+.........+(x-xn)...(x-x1)y[xn,...x0]

• truong hop cac nut cach deu

DT niuton tien:

Pn(x)/x=x0+ht =y0+ t∆y0+ t(t-1)/2! ∆2y0 +....+ t(t-1)..(t-n+1)/n! ∆ny0

DT niuton lui:

Pn(x)/x=xn+ht =yn+ t∆yn+ t(t+1)/2! ∆2yn +....+ t(t+1)..(t+n-1)/n! ∆nyn