Ventana software support forum

The vensim file was attached in my last message... sorry

Hi I have a problem importing data from excel. The data are only available at distinct time points I did try to use the :hold backward: and :look forward" data functions , but obtained the same results with and without these functions... I would to hold bakward data values ... I send to you a s...

Clearly Vesnim does'nt use the determinant of a matrix to compute the inverse. Try the following tittle vensim program : !**************************** liA: (lia1-lia2) ~ ~ | "inv(mat a)"[cola,llA]= invert matrix(mat A[llA,cola],ELMCOUNT(cola)) ~ ~ | "mata *inv( mat A)"[liA,llA]= ...

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

(1 2) = matrix A
(2 4)

invert matrix (a) (wrong!) result is :

(0 .5)
(.5 0)

witn no wranig from vensim !

How to check the problem ?

1/ Do you a way to multiply matrix in vensim ? 2/ Vensim does accept to invert singular (ie wit 0 determinant) matrix, without warning ! for instance invert matrix( 1 2) has result (0 .5) (2 4) (.5 0) is it possible to check the problem ?

Is t possible to close an xls File from a Venapp. I did not see a commande for that, it should be very useful.