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[tmodes <679654@xxxxxxxxxxxxxxxxxx>]

Hi Stephan,

there are 2 type of warnings in levmar.

The first one is of type
#warning Linearly constrained optimization requires LAPACK and was not compiled!

levmar implement different unconstrained and constrained versions of the
Levenberg-Marquard algorithm. Some of the contrained version need LAPACK
to work. But Hugin is only using the unconstrained version. This type of
warning can therefore ignored, at least for Hugin.

The second warning is
#warning LAPACK not available, LU will be used for matrix inversion when computing the covariance; this might be unstable at times

This warning is trigged in code which is used by Hugin. The warning
states that LAPACK could help to calculate the covariance. But as far as
I know Hugin is not using the returned covariance. So LAPACK could help
to make it more robust. But until now I have not seen any issues when
using levmar without LAPACK.

The LAPACK is already in CMake, but needs explicitly activated:
##
## LAPACK (optional, enable by -DENABLE_LAPACK=ON)
##
OPTION (ENABLE_LAPACK "Use LAPACK based solver in levmar" OFF)

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https://bugs.launchpad.net/bugs/679654

Title:
  updated levmar library

Status in Hugin - Panorama Tools GUI:
  Fix Committed

Bug description:
  Last December, an updated levmar was released (2.2), with change that
  could be very interesting for hugin:

   - Fixed an error in the computation of the damping factor of
  levmar_dif()  in lm_core.c. Thanks to John Ervin for reporting.

  This change is interesting, because levmar_dif is used for photometric
  optimisation by hugin.

  I took the liberty to try hugin with this newer version of the levmar
  library, and on my test panorama it took slightly longer but reached
  the same end result.

  This is of course not 0.7 material, but perhaps something for early
  0.7.1.

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