## 28 Interpolation

This chapter describes functions for performing interpolation. The library provides a variety of interpolation methods, including Cubic, Akima, and Steffen splines. The interpolation types are interchangeable, allowing different methods to be used without recompiling. Interpolations can be defined for both normal and periodic boundary conditions. Additional functions are available for computing derivatives and integrals of interpolating functions. Routines are provided for interpolating both one and two dimensional datasets.

These interpolation methods produce curves that pass through each datapoint. To interpolate noisy data with a smoothing curve see Basis Splines.

The functions described in this section are declared in the header files `gsl_interp.h` and `gsl_spline.h`.