QT_Prac_NewtonsBackward_2B

/*
x=[45 50 55 60 65]
y=f(x)=[29 24 21 19 17]
x estimate = 46
Ans:
   27.996288
*/

function[] = newton_bkwd(x,y,xest)
    n=length(y)
    h=x(2)-x(1)
    p=(xest-x(n))/h
    for i=1:n-1
        d(i+1,1)=y(i+1)-y(i)
    end
    for j=2:n
        for i=2:n
            d(i,j)=d(i,j-1)-d(i-1,j-1)
        end
    end
    e(1)=p
    for j=2:n
        e(j)=e(j-1)*(p-1+j)/j
    end
    yest=0;
    for j=1:n
        yest=yest+e(j)*d(n,j)
    end
    yest=yest+y(n)
    disp(yest)
endfunction

x=[45 50 55 60 65]
y=[29 24 21 19 17]
xest=46
newton_bkwd(x,y,xest)