GPL - GSL and derivative work.

[Mark Galassi]

    >> On this list, I simply want to assure anyone that if your
    >> software can only work with GSL then your software is subject
    >> to the relevant parts of the GPL.

    Edwin> The GPL applies only if you distribute your software any
    Edwin> only if you distribute the GPL'd library (GSL) with it.

Of course: I said that you are subject to the relevant parts of the
GPL, so it only applies if you distribute your software.

    Edwin> You cannot copyright the GSL API.  Anybody can implement
    Edwin> the GSL API.

Of course, and once you reimplement GSL then you can say that the
software does not depend on GSL for its functioning.

But until you do, if you distribute software and say "this will only
work with GSL because no other implementation of that API exists" then
you have a derivative work.