Jan,

After looking more carefully on the grafs your commandos give, I see that the graf witch should add up the three others get a smaller value than the grafs one by one.

Output 1 have its largest value 10^-5 at 80 rad/s, and the summed graf have a little over 10^-6 at the same freq.

Using the functions:

sys2 := TransferFunction(sys:-tf[1, 1]+sys:-tf[1, 4]+sys:-tf[1, 5])

BodePlot(sys2, numpoints = 5000, decibels = false, range = 1 .. 0.1e6)

BodePlot(sys, decibels = false, numpoints = 5000, subsystem = [[1, 1], [1, 4], [1, 5]], legend = ["Output 1", "Output 4", "Output 5"])

Am I doing somthing wrong?

Thanks,

Kristian

Thanks for your comment.

If there is of any interest, the system I'm analyzing is a diesel-electric propulsion system on a Norwegian Research-ship with vibration problems on the left engine.

Kristian

Thank you!

It works perfectly.

Kristian

Hi, and thanks for your response.

Under is the entire code.  The reason I get three lines in the graf is because I selects subsystem [1,1] ,[1,4],[1,5]

Is there any posible to add up the values for each line and produce a new one?

I use Maple 12.

Thanks,

Kristian

with(LinearAlgebra), with(DynamicSystems)

> m1 := 3200; m2 := 3200; m3 := 3200; m := 3500; J := 7782; km := 0.3924e8; kr := 0.4986e8; l := 2.315;
>
> M := Matrix([[m1, 0, 0, 0, 0], [0, m2, 0, 0, 0], [0, 0, m3, 0, 0], [0, 0, 0, m, 0], [0, 0, 0, 0, J]]);
 

> K := Matrix([[km, 0, 0, -km, -km*l], [0, km, 0, -km, 0], [0, 0, km, -km, km*l], [-km, -km, -km, 3*km+3*kr, 0], [-km*l, 0, km*l, 0, (2*km+2*kr)*l^2]]);
 

>

> A := M*s^2+K;

> T := Adjoint(A); den := collect(Determinant(A), s);

> sys := TransferFunction(T/den);

> sys:-tf;

BodePlot(sys, decibels = false, subsystem = [[1, 1], [1, 4], [1, 5]])