Unexpected result calculating the determinant of a singular matrix (42S)
10-23-2019, 07:01 AM
Post: #25
 Werner Senior Member Posts: 887 Joined: Dec 2013
RE: Unexpected result calculating the determinant of a singular matrix (42S)
(10-23-2019 04:50 AM)Valentin Albillo Wrote:  But try instead with AM#7, a matrix of the same dimensions (7x7) and similarly-sized integer elements, as detailed in my article
, under "Can it get any worse ?"

Still works..
This time the condition number is about 7e12, and the determinant can be expected to be correct to about 2 digits: .998918882 with F-54 Set.
With F-54 Clear, it's 1 exactly, of course.
A 7x7 matrix with integer elements less than 100 and determinant 1 will always have at least 1 digit correct when the calculations are done with 15 digits, and so the rounding will work.

Now, Valentin, I have always wondered how you created these matrices, and I've asked you once before (a very long time ago, admittedly). Can you shed some light on this?

Cheers, Werner

41CVâ€ ,42S,48GX,49G,DM42,DM41X,17BII,15CE,DM15L,12C,16CE
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 Messages In This Thread Unexpected result calculating the determinant of a singular matrix (42S) - Dave Britten - 10-21-2019, 01:54 AM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Valentin Albillo - 10-21-2019, 02:24 AM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Dave Britten - 10-21-2019, 02:30 AM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Valentin Albillo - 10-21-2019, 02:36 AM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Thomas Okken - 10-21-2019, 03:11 AM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Valentin Albillo - 10-21-2019, 04:23 AM RE: Unexpected result calculating the determinant of a singular matrix (42S) - pinkman - 10-21-2019, 07:39 AM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Moggul - 10-21-2019, 08:41 AM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Thomas Okken - 10-21-2019, 11:37 AM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Valentin Albillo - 10-21-2019, 10:33 PM RE: Unexpected result calculating the determinant of a singular matrix (42S) - John Keith - 10-21-2019, 11:58 AM RE: Unexpected result calculating the determinant of a singular matrix (42S) - ttw - 10-21-2019, 12:48 PM RE: Unexpected result calculating the determinant of a singular matrix (42S) - John Keith - 10-21-2019, 06:12 PM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Dave Britten - 10-21-2019, 01:49 PM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Thomas Okken - 10-21-2019, 03:06 PM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Claudio L. - 10-21-2019, 04:46 PM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Thomas Okken - 10-21-2019, 05:54 PM RE: Unexpected result calculating the determinant of a singular matrix (42S) - toml_12953 - 10-21-2019, 06:00 PM RE: Unexpected result calculating the determinant of a singular matrix (42S) - ttw - 10-21-2019, 07:10 PM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Werner - 10-22-2019, 06:12 AM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Thomas Okken - 10-22-2019, 11:11 AM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Valentin Albillo - 10-23-2019, 04:50 AM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Werner - 10-23-2019 07:01 AM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Valentin Albillo - 10-23-2019, 11:06 PM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Werner - 10-24-2019, 06:34 AM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Valentin Albillo - 10-25-2019, 11:00 PM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Paul Dale - 10-22-2019, 09:23 AM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Werner - 10-22-2019, 12:13 PM RE: Unexpected result calculating the determinant of a singular matrix (42S) - Werner - 10-28-2019, 08:29 AM

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