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From: Janek Kozicki (janek_listy_at_[hidden])
Date: 2006-06-21 18:43:28

Daryle Walker said: (by the date of Wed, 21 Jun 2006 15:49:22 -0400)

> On 6/19/06 12:03 PM, "Geoffrey Irving" <irving_at_[hidden]> wrote:
> > On Mon, Jun 19, 2006 at 09:43:45AM -0600, Dave Steffen wrote:
> [SNIP]
> >> It seems to me that building operations for vectors-with-units and
> >> matrices-with-units is a duplication of effort. If the PQS library
> >> is as easy to use as [ it should be | we think it is ] then
> >> incorporating units into UBLAS should be both easy and a good
> >> exercise.
> >
> > Small vectors and transforms require somewhat different interfaces than
> > large vectors. For example, uBLAS does not have cross products,
> > normalization, quaternions, exponential maps from vectors to quaternions,
> > etc.
> But we have a quaternion library too....

yes, there is Boost.Quaternion library, but it is not suitable for
working with geomnetry. Only math stuff. Several functions are missing,
for example:

  from_rotation_matrix (builds a quaternion)
  from_axis_angle (builds a uaternion)
  operator* (quaternion,vector) (rotates a vector)

and a few others. I have investigated this library a bit, and the author
has done some work in this direction, but finally gave up, because the
only linear algebra library is Boost.Ublas.Numerics which has a bit
unsuitable vector type (mainly because it is designed as a library for
big vectors/matrices, not small vectors/matrices). There were problems
on the interface between Boost.Quaternin and speed issues.

so currently Boost.Quaternion is unusable for our purposes here. I hope
that this will change once Dave's linear algebra library will be

Janek Kozicki                                                         |

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