# Two-variable interpolator This page will let you interpolate a function of two variables. Specify the value of the function at three given points and the page will give an interpolated value at a fourth point.

The three given points must form a triangle, i.e. they cannot all be on a line.

For best results, the point where you want to know the interpolated value should be inside the triangle formed by the given points. Otherwise you’re extrapolating rather than interpolating, and extrapolation is less reliable than interpolation, especially if you're extrapolating far from the given data.

 x y f(x, y) Given Given Given Interpolate

An asterisk after the result means that the value is extrapolated rather than interpolated, i.e. the specified point lies outside the triangle determined by the given points.

If the result is "colinear" than means that the given point lie on a straight line and so it is not possible to carry out the interpolation.

How it works: In a nutshell, the page finds the barycentric coordinates of the point where you want to interpolate, and uses those coordinates as weights in a weighted average of the function values at the vertices of the triangle.

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