From: yoshiki9@...
Date: 2006-08-04T12:42:30+09:00
Subject: Re: Setting precision in Ruby-GSL calculations ?

   Hi Axel, sorry for late reply.

> Ruby-Gsl defines these as  M= U S V^tr,
> where U can have uneven dimensions, but many
> authors require U  to
> be square (and softwares, eg. Mathematica)

   This is because GSL can do so.

> I still don't know why I don't get singular
> values to higher precision  ...
> does one have to convert to Float or something ?

   All the values in Ruby/GSL including elements
in a GSL::Vector object are calculated in double
precision. But when you use e.g.
  irb> p v      or
  irb> v.print
only 4 digits of each element are displayed using
printf() with the format "%4.3e". This does not
mean the precision of 4 significant digits. If you
need to "see" vector elements, you can obtain
them as Ruby Float by accessing with indices as
v[0], v[1].

   If you really need more higher precision better
than double, I have no idea.

   Yoshiki