Hello Federico,
cond() and rcond() do not accept rationals, but the determinant of A is very
close to 0:
--> det(A)
ans =
3.573D-10
0.027s² +7.433D-10s³
This likely explains that the inversion is not relia
Maybe an inversion made in state-space could me more reliable ?
S.
Le 09/03/2020 à 13:36, sgoug...@free.fr a écrit :
Hello Federico,
cond() and rcond() do not accept rationals, but the determinant of A is very
close to 0:
--> det(A)
ans =
3.573D-10
initially I thought could it be possible the number is too small (or too large)
to be handled by double?
after trying scaling down the problem, I notice that in Scilab 6.0.2 onwards:
--> 2e-20*%i
ans =
0.
in Scilab 5.5.2
-->2e-20*%i
ans =
2.000D-20i
Could th
sorry, ignore the previous finding, turn out to be it seems like just a display
issue.
However, I think my initial thought of the precision might be the issue? some
number are too small (first case) and giving error during computation?
thx
rgds,
CL
On Mon, 09 Mar 2020 22:11:43 +
Samuel,
Thanks for your answer. Simply being the determinant small doesn't seem
a problem when using floating point. Probably the bigger problem is the
presence, somewhere, of very dissimile orders of magnitude.
One curious detail in my example is that the solution of the system when
adding
