[IPOL discuss] eig3.c license clarification [Re: the problem with Eigen ...]

[Nicolas Limare]

> - The licences of your first 2 solutions are unclear, and I would
> not include them in my code. I had before the code from Numerical
> Recipes, and its licence clearly does not allow such use. That is
> why I switched to Eigen.

The first one is unclear. The second one says:
/* Eigen decomposition code for symmetric 3x3 matrices, copied from
   the public domain Java Matrix library JAMA. */

JAMA is there: http://math.nist.gov/javanumerics/jama/
Its copyright notice says "This software is a cooperative product of
The MathWorks and the National Institute of Standards and Technology
(NIST) which has been released to the public domain."

Public domain is an US copyright term, which means that the copyright
holders abandon all their rights (this is not possible in France, for
example).

I checked, the eig3.c code comes from the EigenvalueDecomposition.java
file. This java code is derived from EISPACK, itself based on old
ALGOL algorithms. This old code (we are talking about the 70s or 60s)
has no clear license, but it is consideref "free" and it is the base
on which every linear algebra library is built, lapack and
successors.

-- 
Nicolas LIMARE - CMLA - ENS Cachan    http://www.cmla.ens-cachan.fr/~limare/
IPOL - image processing on line                          http://www.ipol.im/
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