To comment on the following update, log in, then open the issue:
http://www.openoffice.org/issues/show_bug.cgi?id=99915
User aw changed the following:
What |Old value |New value
================================================================================
CC|'weiz' |'thb,weiz'
--------------------------------------------------------------------------------
Assigned to|aw |iha
--------------------------------------------------------------------------------
------- Additional comments from [email protected] Fri Apr 3 12:35:29 +0000
2009 -------
AW->IHA: That small value is well balanced to make all kind of linear algebra
stuff work with the double precision values which sadly are not natural
mathematical numbers, but only try to come close to them. All kinds of precision
problems will arise when You change that number, so no, You cannot change it.
All algorithms using the non-ednless double precision values need to be balanced
with a restricting precision value (maybe You will again not believe me here, in
that case look in the net for answers :-).
That small number would even have to be smaller when we would decide to go from
doubles to floats.
The standard convention normally used in basegfx is to have the function call in
a second version where the small number is handed over as last parameter, see
various examples by grepping basegfx. This would mean to add below
void translate(double fX, double fY);
a second method with
void translate(double fX, double fY, const double&
rfSmallValue);
and to implement it accordingly by handing over that value to the used
fTools::equalZero tests which have a SmallValue supportig version. When You do
this, please take the time to add all necessary calls to the implementation of
B2DHomMatrix, others may need it in the future, too.
Another possibility is that You have a numerical problem with floating point in
the sense of numerical mathematics: You may use the wrong numerical method. If
that translation is an added translation with thousands of small moves, the
numerical way is not to translate thousands of time by the small value, but to
collect the combined translation locally and to apply a single one. Tis is done
for precision reasons and was stated in the 70's together with IEEE formats (in
fortran77 at that time).
I will add thb to cc, he may have more information on the topic if needed.
---------------------------------------------------------------------
Please do not reply to this automatically generated notification from
Issue Tracker. Please log onto the website and enter your comments.
http://qa.openoffice.org/issue_handling/project_issues.html#notification
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
