Precision problem with matrix inversion
07-15-2015, 04:59 AM
Post: #9
 cyrille de brĂ©bisson Senior Member Posts: 1,047 Joined: Dec 2013
RE: Precision problem with matrix inversion
Hello,

I can only speak of the numerical mode here.
The matrix inversion and multiplication have been coded with 3 conflicting constraints:
- High precision
- 0 result elements should be 0
- n^3 (not n^4) and memory constraint

Of course, it is not possible to have all 3 at the same time.
- Calculations ARE done in 15 digit precision on a row by row, but are stored in 12 digit (for memory)
- small elements (smaller in magnitude than epsilon*min number) are transformed into 0
- n^3 algorithm

This leads to the behavior that you observed.
If you do want full precision, that is what the CAS is there for.

Cyrille
 « Next Oldest | Next Newest »

 Messages In This Thread Precision problem with matrix inversion - Maro - 07-13-2015, 06:22 PM RE: Precision problem with matrix inversion - roadrunner - 07-13-2015, 06:41 PM RE: Precision problem with matrix inversion - roadrunner - 07-13-2015, 06:58 PM RE: Precision problem with matrix inversion - Maro - 07-13-2015, 07:24 PM RE: Precision problem with matrix inversion - roadrunner - 07-13-2015, 10:00 PM RE: Precision problem with matrix inversion - Didier Lachieze - 07-13-2015, 10:40 PM RE: Precision problem with matrix inversion - Maro - 07-14-2015, 05:58 AM RE: Precision problem with matrix inversion - Anders - 07-14-2015, 04:31 AM RE: Precision problem with matrix inversion - cyrille de brĂ©bisson - 07-15-2015 04:59 AM RE: Precision problem with matrix inversion - Maro - 07-15-2015, 06:25 AM RE: Precision problem with matrix inversion - Paul Dale - 07-15-2015, 07:15 AM RE: Precision problem with matrix inversion - Anders - 07-15-2015, 08:28 PM RE: Precision problem with matrix inversion - Maro - 07-16-2015, 08:23 AM RE: Precision problem with matrix inversion - Thomas Radtke - 07-16-2015, 11:03 AM RE: Precision problem with matrix inversion - parisse - 07-15-2015, 05:47 AM RE: Precision problem with matrix inversion - Maro - 07-15-2015, 06:42 AM RE: Precision problem with matrix inversion - parisse - 07-15-2015, 07:46 AM RE: Precision problem with matrix inversion - Maro - 07-15-2015, 08:20 AM RE: Precision problem with matrix inversion - parisse - 07-15-2015, 12:45 PM RE: Precision problem with matrix inversion - Werner - 07-16-2015, 01:31 PM RE: Precision problem with matrix inversion - parisse - 07-17-2015, 08:18 AM RE: Precision problem with matrix inversion - Dirk. - 07-17-2015, 09:07 AM

User(s) browsing this thread: 2 Guest(s)