Hello,
Firstly, I am sorry for my bad english. I have a problem and I need help. I am writting a code that calculate minimum time on light curve with four methods (polynomial, fourier, Cubic Spline, bisector of chord). But I dont know calculate error of minimum times. For example,

I fit 10 degree polynomial on light curve as shown above figure. I create 1000 points between first point and last point in x-axis. Later I put those points in equation of polynomial. corresponding of minimum value in y-axis at x-axis is minimum time. But how can I calculate error of minimum time at 4 methods
Firstly, I am sorry for my bad english. I have a problem and I need help. I am writting a code that calculate minimum time on light curve with four methods (polynomial, fourier, Cubic Spline, bisector of chord). But I dont know calculate error of minimum times. For example,

I fit 10 degree polynomial on light curve as shown above figure. I create 1000 points between first point and last point in x-axis. Later I put those points in equation of polynomial. corresponding of minimum value in y-axis at x-axis is minimum time. But how can I calculate error of minimum time at 4 methods