find inflection point from given input point data

i have input points

x=[0     1     2     3     4     5     6     7     8     9    10]

y=[5.0000    6.0000    8.0000    9.0000    8.5000    8.0000    7.0000    6.5000    7.0000    8.0000   10.0000]

x1=0:0.001:10;

y1=interp1(x,y,x1,'spline');

plot(x1,y1);

i want to find inflection points on that curve?

what if there are more than 1 inflection point in a curve?

explain with full code please.