Approximation: Bezier curve

 

Both x and y are calculated by

 

and

 

as in 418 of G of GAUSS. We set 0<=t<=1.

 

The term is called Bernstein polynomial.

 

 If we set many points, the resulting curve is streatched out and it fits well.

 

 

where the curve is almost linear locally and it suits the result of gird method.