x0=[0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23];
y0=[0 0 0 -2 -2 -3 -4 -4 -4 2 5 8 9 10 11 11 10 10 6 5 3 2 1 3.33];
x=0:1/60:23;
y1=interp1(x0,y0,x);
y2=interp1(x0,y0,x,'spline');
pp1=csape(x0,y0);
y3=ppval(pp1,x);
pp2=csape(x0,y0,'not-a-knot');
y4=ppval(pp2,x);
pp3=csape(x0,y0,[-1,y0,-2],[1,1]);
y5=ppval(pp3,x);
[x',y1',y2',y3',y4'];
subplot(1,1,1)
plot(x,y1,'b--',x,y4,'k-',x0,y0,'k.');
hold on
for i=1:length(x0)
text(x0(i),y0(i),num2str(y0(i))); %把 num2str(y(i))中的 y(i)改成 y(i)/2
End
title('Spline1')