untitled11.m

这是用牛顿法做的

x=[1 2];
y=[2 3];
ydot=[1 -1];
syms xi
k=1;
yii=y(k)*(1-2*(xi-x(k))/(x(k)-x(k+1)))*(xi-x(k+1))^2/(x(k)-x(k+1))^2+y(k+1)*(1-2*(xi-x(k+1))/(x(k+1)-x(k)))*(xi-x(k))^2/(x(k+1)-x(k))^2+ydot(k)*(xi-x(k))*(xi-x(k+1))^2/(x(k)-x(k+1))^2+ydot(k+1)*(xi-x(k+1))*(xi-x(k))^2/(x(k+1)-x(k))^2
yi= collect(yii)