function [xmin,ymin]=parab(func,x1,x2,x3)
y1=func(x1);
y2=func(x2);
y3=func(x3);
x=[x1 x2 x3]
y=[y1 y2 y3]
delta=(x2-x1)*(x3-x1)*(x3-x2);
A=((x3-x2)*y1-(x3-x1)*y2+(x2-x1)*y3)/delta;
B=(-(x3^2-x2^2)*y1+(x2^2-x1^2)*y2-(x2^2-x1^2)*y3)/delta;
C=(x2*x3*(x3-x2)*y1-x1*x3*(x3-x1)*y2+x1*x2*(x2-x1)*y3)/delta;
xmin=-B/(2*A);
ymin=-B*B/(4*A)+C;
end