# Package org.apache.commons.math3.fitting.leastsquares

package org.apache.commons.math3.fitting.leastsquares
This package provides algorithms that minimize the residuals between observations and model values. The `least-squares optimizers` minimize the distance (called cost or χ2) between model and observations.
Algorithms in this category need access to a problem (represented by a `LeastSquaresProblem`). Such a model predicts a set of values which the algorithm tries to match with a set of given set of observed values.
The problem can be created progressively using a `builder` or it can be created at once using a `factory`.

Since:
  3.3

Related Packages
Package
Description
org.apache.commons.math3.fitting
Classes to perform curve fitting.
Class
Description
AbstractEvaluation
An implementation of `LeastSquaresProblem.Evaluation` that is designed for extension.
EvaluationRmsChecker
Check if an optimization has converged based on the change in computed RMS.
GaussNewtonOptimizer
Gauss-Newton least-squares solver.
GaussNewtonOptimizer.Decomposition
The decomposition algorithm to use to solve the normal equations.
LeastSquaresAdapter
An adapter that delegates to another implementation of `LeastSquaresProblem`.
LeastSquaresBuilder
A mutable builder for `LeastSquaresProblem`s.
LeastSquaresFactory
A Factory for creating `LeastSquaresProblem`s.
LeastSquaresOptimizer
An algorithm that can be applied to a non-linear least squares problem.
LeastSquaresOptimizer.Optimum
The optimum found by the optimizer.
LeastSquaresProblem
The data necessary to define a non-linear least squares problem.
LeastSquaresProblem.Evaluation
An evaluation of a `LeastSquaresProblem` at a particular point.
LevenbergMarquardtOptimizer
This class solves a least-squares problem using the Levenberg-Marquardt algorithm.
MultivariateJacobianFunction
A interface for functions that compute a vector of values and can compute their derivatives (Jacobian).
ParameterValidator
Interface for validating a set of model parameters.
ValueAndJacobianFunction
A interface for functions that compute a vector of values and can compute their derivatives (Jacobian).