# Having Dynamic evaluated when off screen

As the title says, I want a cell containing the dynamic solution of a DAE-System to be available over the whole document. I use a lot of different Plots and Sliders scattered over the document and it is pretty annoying that after the cell scrolled off screen, the dynamic stuff stops working altogether (as this is the nature of Dynamic as the documentation explains it). If I copy Dynamic[Solution] and insert it all over the place everything works perfectly fine but does of course look unprofessional. Therefore I tried DynamicWrapper["This is a text", Dynamic[Solution]] to hide Dynamic[Solution] inside titles and texts that are scattered around anyway. This does however not work as I imagined it must.

If someone has an idea how to comfortably solve the issue I would be glad.

Edit: The system is a scale that works by compensation method; some code:

This is my variable called solution

solution =
Dynamic[sol2 =
Quiet[NDSolve[{d1'[t] == d2[t],
d2'[t] == k*d1[t] + b*d2[t] + (ki*l)/\[Theta][t]*d3[t] + (l*g)/\[Theta][t]*
(mersatz - mass[t, offset, Mass]),
d3'[t] == -((ki*l)/L)*d2[t] - R/L*d3[t] + (U[t] + Uoffset)/L,
U[t] == kP*U2[t] + kI*IntegralPart[t] + kD*U2'[t],
U2[t] == -ks*l* d1[t],
D[IntegralPart[t], {t, 1}] == U2[t],
d1[0] == 0, d2[0] == 0, d1'[0] == 0,
d2'[0] == (l*ki)/\[Theta][0]*Uoffset/R + (l*g)/\[Theta][0]*
(mersatz - mass[0, offset, Mass]),
d3'[0] == 0, d3[0] == Uoffset/R , U[0] == 0, U2[0] == 0,
IntegralPart[0] == 0}, {d1, d2 , d3, U, U2, IntegralPart}, {t,
0, duration}
]]]


After that follows a big plot of the measured / calculated load on my scale

PlotWeight =
Manipulate[
Quiet[Plot[{measuredweight[t] /. sol2,
If[referencew == 1, mass[t, offset, Mass], ""]} , {t, 0,
duration}, PlotStyle -> {Automatic, Darker[Green]},
ImageSize -> {1200, 400}, AspectRatio -> Full,
ExclusionsStyle -> {Darker[Green], None},
AxesLabel -> {Style["time [s]", FontFamily -> font1],
Style["measured weight [kg]", FontFamily -> font1]},
PlotRange -> {{0, duration}, If[scale == 1, Full, {0, scale}]}]],
Style["      +", 12]
, {{scale, 1,
Rotate[Style["AxisScale", FontFamily -> font1, FontSize -> 12],
90 \[Degree] ]}, 0.01, 1, ControlType -> VerticalSlider},
Style["      -",
12], {{referencew, 0,
Style["activate weight reference", FontFamily -> font1,
FontSize -> 12]} , {0, 1}},
ControlPlacement -> {Left, Left, Left, Top}, Alignment -> Center ]


Other variables displayed in interactive Plots are current, voltage, angular velocity, angle, etc. All those are coming from the DAE that is fitted in solution (in the variable sol2 inside of solution).

A full picture in this Pdf.

-
Why do you want it available when you can't see it? You have sliders but you can't see the solution, right? –  Rojo Nov 11 '12 at 18:46
In any case, there are alternatives. From scheduled tasks, to a notebook dynamic expression, to a dynamic docked cell. But I ask because probably there's a design issue here –  Rojo Nov 11 '12 at 18:47
The variable solution is used in Plots around the documents (with individual Sliders for individual plots) in the fashion: Plot[U[t] /.solution ...] –  Sascha Nov 11 '12 at 18:53
You can run this CurrentValue[InputNotebook[], DockedCells] = (Pause[3]; NotebookRead[InputNotebook[]]) and as soon as you evaluate you have 3 seconds to select the cell you want to get docked and wait for it >P –  Rojo Nov 11 '12 at 19:24
It seems odd that solution as a variable defined here is Dynamic[(*some stuff*)] while the comments above suggest that solution is used in the form Plot[U[t]/.solution...]. As Rojo says, there are many possible answers to the question, but I just don't feel I understand the question well enough to say which (if any) of them are appropriate for you. Incidentally, an additional tool I would add to Rojo's list is the use of notebook-level TaggingRules to emulate notebook-level DynamicModule variables. See the examples section of the TaggingRules docs for more info. –  John Fultz Nov 11 '12 at 22:06

FrontEndDynamicExpression -> Dynamic[expr] causes the expression to be tracked and updated in the usual way, except that expr is not displayed anywhere.
FrontEndDynamicExpression can be set using SetOptions[scope,FrontEndDynamicExpression->Dynamic[expr]], where scope can be $FrontEnd or $FrontEndSession.
You may also consider using CellDynamicExpression.
In any case, Dynamic used without any TrackedSymbols specification is usually very inefficient as it will update much more often that what you need, or even, depending on your code, before you need it.