Re: Fwd: Copyright infringement in linux/drivers/usb/serial/keyspan*fw.h

[Andreas Jaeger <aj@suse.de>]

Aaron Lehmann <aaronl@vitelus.com> writes:

> On Fri, May 25, 2001 at 02:34:05AM -0400, Alexander Viro wrote:
> > Should we file bug reports against glibc?
> 
> invsqrtpi=  5.64189583547756279280e-01
> Inverted square root of pi. Want to file a bug on Pi?
> 
> tpi      =  6.36619772367581382433e-01,
> R0/S0 on [0, 2.00]
> 
> I'm not sure what R and S are, but the glibc developers probably are.

We have comments in the code that state how j0 is build, and R0/S0
come from some expansion:
 * Bessel function of the first and second kinds of order zero.
 * Method -- j0(x):
 *	1. For tiny x, we use j0(x) = 1 - x^2/4 + x^4/64 - ...
 *	2. Reduce x to |x| since j0(x)=j0(-x),  and
 *	   for x in (0,2)
 *		j0(x) = 1-z/4+ z^2*R0/S0,  where z = x*x;
 *	   (precision:  |j0-1+z/4-z^2R0/S0 |<2**-63.67 )

Andreas
-- 
 Andreas Jaeger
  SuSE Labs aj@suse.de
   private aj@arthur.inka.de
    http://www.suse.de/~aj