#9543: Enable cephes on FreeBSD
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Reporter: pjeremy | Owner: pjeremy
Type: defect | Status: new
Priority: major | Milestone: sage-5.6
Component: FreeBSD | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers: Stephen
Montgomery-Smith
Authors: Peter Jeremy, Jean-Pierre Flori | Merged in:
Dependencies: | Stopgaps:
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Comment (by stephen):
Regarding testing the cephes library - I don't think it is fair to
expect them to give super accurate answers. I believe that the linux
library functions will fail in the same way. Same with OpenBSD.
I have been working with the FreeBSD people to get the C99 math
functions into FreeBSD. They are remarkably fussy. I have been working
on the complex arc-trig functions casin(h), cacos(h), catan(h), and I
have written some extremely well tested and verified code which is
listed here: http://www.math.missouri.edu/~stephen/software/#catrig
Nevertheless they still won't commit my programs until I have made some
style corrections, and I don't have time right now to do this.
The only other package I know of that implements these functions well
are the boost libraries. And even those were buggy (my bug fixes were
recently accepted by them).
Another person is working on clog. The real part of clog(z) is
particularly hard to implement in the case that |z| is close to one.
The linux and OpenBSD libraries totally disregard the issues that give
rise to the huge errors.
And for casinh and cacosh, even the mpc libraries are badly written in
that their only saving grace is that they keep increasing the number of
internal digits until they are sure that their answer is correct. (If
you wanted something like 200 bits of accuracy for cacosh, some inputs
can take minutes to compute.)
Anyway, all this is to say that you shouldn't hold the cephes libraries
up to any kind of high standard. Treat them as work arounds so that
ccosh and such like will actually be compiled into sage on FreeBSD,
rather that the answers should be particularly accurate.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9543#comment:17>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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