Tool to find the equation of a function from its points, its coordinates x, y=f(x) according to some interpolation methods and equation finder algorithms

Function Equation Finder - dCode

Tag(s) : Functions

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To find the equation from a graph:

Method 1 (fitting): analyze the curve (by looking at it) in order to determine what type of function it is (rather linear, exponential, logarithmic, periodic etc.) and indicate some values in the table and dCode will find the function which comes closest to these points.

Method 2 (interpolation): from a finite number of points, there are formulas allowing to create a polynomial which passes exactly through these points (see Lagrange interpolation), indicate the values of certain points and dCode will calculate the passing polynomial by these points.

To derive the equation of a function from a table of values (or a curve), there are several mathematical methods.

Method 1: **detect remarkable solutions**, like remarkable identities, it is sometimes easy to find the equation by analyzing the values (by comparing two successive values or by identifying certain precise values).

__Example:__ a function has for points (couples $ (x,y) $) the coordinates: $ (1,2) (2,4), (3,6), (4,8) $, the ordinates increase by 2 while the abscissas increase by 1, the solution is trivial: $ f (x) = 2x $

Method 2: **use a interpolation function**, more complicated, this method requires the use of mathematical algorithms that can find polynomials passing through any points. The most well known interpolations are Lagrangian interpolation, Newtonian interpolation and Neville interpolation.

NB: for a given set of points there is an infinity of solutions because there are infinite functions passing through certain points. dCode tries to propose the most simplified solutions possible, based on affine function or polynomial of low degree (degree 2 or 3).

To find the equation of a straight line, see the page: linear equation.

dCode retains ownership of the online "Function Equation Finder" source code. Except explicit open source licence (indicated CC / Creative Commons / free), the "Function Equation Finder" algorithm, the applet or snippet (converter, solver, encryption / decryption, encoding / decoding, ciphering / deciphering, translator), or the "Function Equation Finder" functions (calculate, convert, solve, decrypt / encrypt, decipher / cipher, decode / encode, translate) written in any informatic language (Python, Java, PHP, C#, Javascript, Matlab, etc.) and all data download, script, copy-paste, or API access for "Function Equation Finder" are not public, same for offline use on PC, tablet, iPhone or Android ! Remainder : dCode is free to use.

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equation,coordinate,curve,point,interpolation,table

Source : https://www.dcode.fr/function-equation-finder

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