invert matrix

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cchab
Junior Member
Posts: 7
Joined: Fri Feb 11, 2005 4:33 pm

invert matrix

Post by cchab »

Clearly Vensim does accept to invert a matrix with a determinant close or equal to 0 !!

A minimal improve should be a warning (as done by most statistical software).

Regards
LAUJJL
Senior Member
Posts: 1477
Joined: Fri May 23, 2003 10:09 am
Vensim version: DSS

inverting matirx

Post by LAUJJL »

you are right, it inverts the matrix giving weird results. It is to the administrators staff to provide an answer or to modify later releases.
J.J.L
LAUJJL
Senior Member
Posts: 1477
Joined: Fri May 23, 2003 10:09 am
Vensim version: DSS

inverting a matrix

Post by LAUJJL »

Calculating the determinant of a matrix by an algebrical method, requires a very high number of calculations.
With an array of 20 x 20 values, or a projection of a 20 dimensions space to a 20 dimensions space, you need to perform 20! (factorial 20) calculations!
as one needs to calculate the determinant of the sub matrix associated with any column or line of the matrix.
Hope that you have not too big matrixes.
Regards.
J.J. Laublé
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