# Documentation

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# Interpolation

Gridded and scattered data interpolation, data gridding, piecewise polynomials

Interpolation is a technique for adding new data points within a range of a set of known data points. You can use interpolation to fill-in missing data, smooth existing data, make predictions, and more. Interpolation in MATLAB® is divided into techniques for data points on a grid and scattered data points.

## Functions

 `interp1` 1-D data interpolation (table lookup) `interp2` Interpolation for 2-D gridded data in meshgrid format `interp3` Interpolation for 3-D gridded data in meshgrid format `interpn` Interpolation for 1-D, 2-D, 3-D, and N-D gridded data in ndgrid format `griddedInterpolant` Gridded data interpolation `pchip` Piecewise Cubic Hermite Interpolating Polynomial (PCHIP) `spline` Cubic spline data interpolation `ppval` Evaluate piecewise polynomial `mkpp` Make piecewise polynomial `unmkpp` Extract piecewise polynomial details `padecoef` Padé approximation of time delays `interpft` 1-D interpolation (FFT method)
 `ndgrid` Rectangular grid in N-D space `meshgrid` 2-D and 3-D grids
 `griddata` Interpolate 2-D or 3-D scattered data `griddatan` Interpolate N-D scattered data `scatteredInterpolant` Interpolate 2-D or 3-D scattered data

## Topics

Gridded and Scattered Sample Data

Introduction to interpolating gridded and scattered data sets.

Interpolating Gridded Data

Interpolation of regularly spaced, axis-aligned data sets.

Interpolation of Multiple 1-D Value Sets

This example shows how to interpolate three 1-D data sets in a single pass using `griddedInterpolant`.

Interpolation of 2-D Selections in 3-D Grids

This example shows how to reduce the dimensionality of the grid plane arrays in 3-D to solve a 2-D interpolation problem.

Resample Image with Gridded Interpolation

This example shows how to use `griddedInterpolant` to resample the pixels in an image.

Interpolating Scattered Data

Interpolating scattered data using `scatteredInterpolant`.

Extrapolating Scattered Data

Extrapolating scattered data using `scatteredInterpolant`.

Normalize Data with Differing Magnitudes

This example shows how to use normalization to improve scattered data interpolation results with `griddata`.

Interpolation Using a Specific Delaunay Triangulation

Perform nearest-neighbor and linear interpolation on a scattered set of points using a specific Delaunay triangulation.