# Wolfram Language & System 11.0 (2016)|Legacy Documentation

This is documentation for an earlier version of the Wolfram Language.
WOLFRAM LANGUAGE GUIDE

# Curve Fitting & Approximate Functions

Built into the Wolfram Language are state-of-the-art constrained nonlinear fitting capabilities, conveniently accessed with models given directly in symbolic form. The Wolfram Language also supports unique symbolic interpolating functions that can immediately be used throughout the system to efficiently represent approximate numerical functions.

## ReferenceReference

FindFit find a general nonlinear fit, potentially including parameter constraints

Fit linear least-squares fit to a list of symbolic functions

LeastSquares solution to a least-squares problem in matrix form

Interpolation find an interpolation to data in any number of dimensions

InterpolatingFunction represent an approximate function to be evaluated repeatedly

InterpolatingPolynomial construct a symbolic interpolating polynomial

### Peak Analysis

FindPeaks find the positions of peaks

EstimatedBackground estimate a smooth background

### Symbolic Formula Discovery

FindFormula attempt to find a simple symbolic formula for data