[Algorhtim]Curve fitting, Interpolation, Apporoximation

. Curve fitting
  . Interpolation : 모든 control point를 지나야 함.
  control point가 많으면 noisy해짐(oscillatory feature)
  Lagrange, Hermite, Cubic spline, B-spline, piece-wise method
  참고) Numerical Analysis
  . Approximation : 모든 control point를 지날 필요 없음.
  control point가 많아도 smooth하다.