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Precision problem with matrix inversion
07-15-2015, 04:59 AM
Post: #9
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
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RE: Precision problem with matrix inversion - cyrille de brébisson - 07-15-2015 04:59 AM



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