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This is the home page of lmfit, a self-contained C library for Levenberg-Marquardt least-squares minimization and curve fitting.


  • 20dec18: Release 8.1 restores pkg-config support, and puts tests under CTest control.
  • 19sep18: Release 8.0 new function lmmin2 estimates parameter errors and covariance matrix.
  • 27feb18: Release 7.0 with API change to avoid unnecessary computations of f-y.
  • 22nov17: Release 6.4 with support for CMake and fittest (still undocumented)
  • 03nov17: Release 6.3 with small corrections and changes in the verbose output
  • 27oct17: Release 6.2, stepping back when norm got infinite.
  • 2dec15: Release 6.1 with new overview man page lmfit(7).
  • 24nov15: Release 6.0 with new wrapper lmcurve_tyd() for data with error bars, and a few more 'const' qualifiers in the API of lmcurve() and lmmin().

For earlier changes, see CHANGELOG



For a gentle introduction to the Levenberg-Marquardt algorithm, see e.g. K Madsen, H B Nielsen, O Tingleff (2004): Methods for non-linear least squares problems.



Download and installation


From Source

Download locations:

Build&install are based on CMake. Out-of-source build is enforced. After unpacking the source, go to the source directory and do:

mkdir build
cd build
cmake ..
make install

To test, run examples in directory demo.

RPM Binaries