Enter the coordinate points and slopes of two dependent lines into the calculator to calculate a third value, P, using bi-linear interpolation.

## Double Interpolation Formula

The following equation can be used to calculate a value from a double interpolation.

## What is double interpolation?

Double interpolation is a mathematical technique used to estimate values in a two-dimensional grid by interpolating between known values. It is particularly useful when the available data points are insufficient to determine a desired value directly.

Imagine a scenario where you have a grid of data points with values given at specific coordinates. However, you need to determine the value at a location within this grid that does not have a known value. This is where double interpolation comes into play.

The process involves two steps. First, interpolation is performed in one direction, usually horizontally, between two known values on the same row or column. This interpolated value is then used as an additional data point for the second interpolation step, which is performed in the other direction, typically vertically. By repeating this process, a more accurate estimation of the desired value is obtained.

Double interpolation is important because it allows us to fill in missing values and make predictions within a grid of data points.