Interface to the 'sparseLM' Levenberg-Marquardt Library R package sparseLM version 0.5 Provides an R interface to the 'sparseLM' C library for large-scale nonlinear least squares problems with arbitrarily sparse Jacobians. The underlying solver implements a sparse variant of the Levenberg-Marquardt algorithm for minimizing sum-of-squares objective functions, supports user-supplied analytic Jacobians or finite-difference approximation, and is designed to exploit sparsity for improved memory use and performance. This package exposes the solver in R and uses sparse matrix classes and the 'CHOLMOD' sparse Cholesky factorization routines through the 'Matrix' package interface. Methods from the C library are described in Lourakis (2010) <doi:10.1007/978-3-642-15552-9_4>. Software Depends: Matrix Imports: methods LinkingTo: Matrix Colin Smith <colin.smith@wesleyan.edu> Comprehensive R Archive Network (CRAN) Colin Smith [aut, cre] (ORCID: <https://orcid.org/0000-0002-4651-167X>), Manolis Lourakis [aut] (ORCID: <https://orcid.org/0000-0003-4596-5773>) GPL-2 2026-03-30 application/tgz https://CRAN.R-project.org/package=sparseLM doi:10.32614/CRAN.package.sparseLM