It is possible to include more than two points, and averaging the slope of the linear interpolant, by regression -like techniques, on the data points chosen to be included.
Diferența dintre extrapolare și interpolare by Courtney Taylor Share on Facebook Share on Twitter Extrapolarea și interpolarea sunt folosite pentru estimarea valorilor ipotetice pentru o variabilă bazată pe alte observații.
This is similar to linear prediction. Polynomial[ edit ] Lagrange extrapolations of the sequence 1,2,3.
Aveți nevoie de ajutor suplimentar?
Extrapolating by 4 leads to a polynomial of minimal degree cyan line. A polynomial curve can be created through the entire known data or just near the end two points for linear extrapolation, three points for linie de tendință de extrapolare extrapolation, etc.
Extras din document Extrapolarea constă, în esenţă, în prelungirea în viitor a evoluţiei constatate în trecut.
The resulting curve can then be extended beyond the end of the known data. Polynomial extrapolation is typically done by means of Lagrange interpolation or using Newton's method of finite differences to create a Newton series that fits the data.
The resulting polynomial may be used to extrapolate the data.
1.2 Interpolare liniară
High-order polynomial extrapolation must be used with due care. For the example data set and problem in the figure above, anything above order 1 linear extrapolation will possibly yield unusable values; an error estimate of the extrapolated value will grow with the degree of the polynomial extrapolation.
This is related to Runge's phenomenon. Conic[ edit ] A conic section can be created using five points near the end of the known data. If the conic section created is an ellipse or circlewhen extrapolated it will loop back and rejoin itself.
Există un număr mare de software specializat în acest domeniu. Din păcate, nu toți utilizatorii știu că un procesor convențional de foi de calcul Excel are în arsenalul său instrumente pentru efectuarea prognozării, care nu sunt inferioare în ceea ce privește eficacitatea programelor profesionale.
An extrapolated parabola or hyperbola will not rejoin itself, but may curve back relative to the X-axis. This type of extrapolation could be done with a conic sections template on paper or with a computer.
French curve[ edit ] French curve extrapolation is a method suitable for any distribution that has a tendency to be exponential, but with accelerating or decelerating factors. Another study has shown that extrapolation can produce the same quality of forecasting results as more complex forecasting strategies.
If the method assumes the data are smooth, then a non- smooth function will be poorly extrapolated. In terms of complex time series, some experts have discovered that extrapolation is more accurate when performed through the decomposition of causal forces.
The classic example is truncated power series representations of sin x and related trigonometric functions.
How to Extrapolate Excel Graph
This divergence is a specific property of extrapolation methods and is only circumvented when the functional forms assumed by the extrapolation method inadvertently or intentionally due to additional information accurately represent the nature of the function being extrapolated. For particular problems, this additional information may be available, but in the general case, it is impossible to satisfy all possible function behaviors with a workably small set of potential behavior.
In the complex plane[ edit ] In complex analysisa problem of extrapolation may be converted into an interpolation problem by the change of variable z.