Re: Can we freely use AMOS in Octave?

[Steven G. Johnson]

Dmitri A. Sergatskov wrote:
> On Fri, Aug 10, 2012 at 12:14 PM, Steven G. Johnson
> <address@hidden> wrote:
>
> > As an alternative, I am evaluating a package called COULCC (also written
> > in the 1980s).  COULCC, like AMOS, was also posted without a copyright
> > license, and later published in a journal (Computer Physics Communications, CPC:
> > see http://dx.doi.org/10.1016/0010-4655(85)90025-6 ) that distributes
> > code under a semi-free (non-commercial-use) license.  However, CPC (unlike
> > ACM) explicitly says that authors retain the copyright on the code, and
> > I was able to contact the COULCC author yesterday and graciously provided
> > me with a version of his code under the MIT/X11 license.
> >
> > COULCC has some potential technical advantages over AMOS, separate from
> > the legal questions.  It can evaluate Bessel functions of complex order
> > in addition to complex arguments (AMOS only handles complex arguments
> > and real orders), and has routines to compute J and Y simultaneously,
> > as well as variants (modified Bessel functions, spherical Bessel
> > functions, Hankel functions, exponentially scaled Bessel and Hankel
> > functions, and Coulomb wavefunctions).
> >
> > (COULCC was originally written in Fortran 77, but the version I now have
> > has been updated with a little bit of Fortran 90 code.  It probably
> > requires a bit of work to make it convenient to call from C/C++, and is
> > currently non-reentrant.)
>
> It appears to me that COULCC is a part of the Fresco coide
> http://www.fresco.org.uk/download.htm
> with a FRES version available "for public distribution"
> (I do not see an explicit licensing):
>
> http://www.fresco.org.uk/source/fres-v29.html

I received a copy of COULCC with an explicit MIT/X11 license directly 
from the original author.  This version of the code (including the 
permission email from the author), along with a re-entrant C++ 
translation that I created (semi-automated, but not f2c), is available at:

    http://jdj.mit.edu/~stevenj/coulcc-20120813.tgz

However, the code (both the Fortran original and my C++ translation) has 
a problem that turned up in my evaluation: it has significantly worse 
accuracy than AMOS for some moderate-size Bessel orders (~ 10).  The 
original author is taking a look at this, but at the moment it may be 
problematic as a drop-in replacement for AMOS.

However, AMOS's inclusion in SLATEC, which has an explicit public-domain 
statement by the national laboratories, seems like it may fix the 
licensing problem with AMOS and eliminate the need for ACM permission.

Steven