Skip to main content

Can Table be used inside Manipulate?


EDIT: CHanged the code. Please try again t see if it works well on our PCs.


I am creating a simple Manipulate[] notebook. However when I place Table[] in the code, like:


Manipulate[ 
OK = True;


ai = ConstantArray[0, MaxIter + 1];
bi = ConstantArray[0, MaxIter + 1];

ci = ConstantArray[0, MaxIter + 1];
ai[[1]] = a0; bi[[1]] = b0; ci[[1]] = (ai[[1]] + bi[[1]])/2;
Table[ (*This instruction causes problems*)
a = ai[[j - 1]]; b = bi[[j - 1]]; c = ci[[j - 1]];
If[(f /. x -> a) (f /. x -> c) <= 0, ai[[j]] = ai[[j - 1]];
bi[[j]] = ci[[j - 1]];,
If[(f /. x -> b) (f /. x -> c) <= 0, ai[[j]] = ci[[j - 1]];
bi[[j]] = bi[[j - 1]];, OK = False; break;];];
ci[[j]] = (ai[[j]] + bi[[j]])/2;
, {j, 2, i}];


If[OK, Show[Plot[f, {x, a0, b0}, PlotStyle -> Thick],
PlotLabel -> "Metoda bisekcji", ImageSize -> Large]]
,
(*controls*)

Dynamic@Column@{
Control[{{f, x^2 - 1, "f(x)="}, {x^2 - 1, Cos[x] - x}}],
Control[{{method, "Bisekcji", "Metoda:"}, {"Bisekcji", "Newtona",
"Iteracji prostej", "Siecznych"}}],

Sequence @@
If[method == "Bisekcji" ||
method ==
"Siecznych" , {Control[{{a0, 1/2,
"\!\(\*SubscriptBox[\(a\), \(0\)]\)="}}],
Control[{{b0, 2,
"\!\(\*SubscriptBox[\(b\), \(0\)]\)="}}]}, {Control[{{x0, 2,
"\!\(\*SubscriptBox[\(x\), \(0\)]\)="}}]}],
Control[{{i, 1, "Iteracja"}, 1, 5, 1}]
},

(*Initialization*)
Initialization :> (
MaxIter = 5;
)
]

The cell containing the GUI keeps evaluating all the time and the displayed content keeps being refreshed and looks like shaking. Is it normal?



Answer



The problem is that some variables are set in the main body of the Manipulate every time the Manipulate is updated. This triggers another update...ad infinitum.


Use TrackedSymbols to control when an update is triggered.



Manipulate[OK = True;
ai = ConstantArray[0, MaxIter + 1];
bi = ConstantArray[0, MaxIter + 1];
ci = ConstantArray[0, MaxIter + 1];
ai[[1]] = a0; bi[[1]] = b0; ci[[1]] = (ai[[1]] + bi[[1]])/2;
Table[(*This instruction causes problems*)a = ai[[j - 1]];
b = bi[[j - 1]]; c = ci[[j - 1]];
If[(f /. x -> a) (f /. x -> c) <= 0, ai[[j]] = ai[[j - 1]];
bi[[j]] = ci[[j - 1]];,
If[(f /. x -> b) (f /. x -> c) <= 0, ai[[j]] = ci[[j - 1]];

bi[[j]] = bi[[j - 1]];, OK = False; break;];];
ci[[j]] = (ai[[j]] + bi[[j]])/2;, {j, 2, i}];
If[OK, Show[Plot[f, {x, a0, b0}, PlotStyle -> Thick],
PlotLabel -> "Metoda bisekcji", ImageSize -> Large]],

(*controls*)
Dynamic@Column@{Control[{{f, x^2 - 1, "f(x)="}, {x^2 - 1,
Cos[x] - x}}],
Control[{{method, "Bisekcji", "Metoda:"}, {"Bisekcji", "Newtona",
"Iteracji prostej", "Siecznych"}}],

Sequence @@
If[method == "Bisekcji" ||
method ==
"Siecznych", {Control[{{a0, 1/2,
"\!\(\*SubscriptBox[\(a\), \(0\)]\)="}}],
Control[{{b0, 2,
"\!\(\*SubscriptBox[\(b\), \(0\)]\)="}}]}, {Control[{{x0, 2,
"\!\(\*SubscriptBox[\(x\), \(0\)]\)="}}]}],
Control[{{i, 1, "Iteracja"}, 1, 5, 1}]},


TrackedSymbols :> {i, a0, b0, method, f},

(*Initialization*)Initialization :> (MaxIter = 5;)]

The rest of it needs work, apparently, but TrackedSymbols solves the continual-updating problem. One can also simply set TrackedSymbols -> True to track only the control variables.


Comments

Popular posts from this blog

list manipulation - Selecting multiple columns from a matrix?

Sample data: data = { {{2013, 1, 1}, 24.13, 167.67, 231.82}, {{2013, 1, 2}, 32.15, 170.92, 225.99}, {{2013, 1, 3}, 35.43, 172.68, 221.67}, {{2013, 1, 4}, 36.73, 173.05, 218.32}, {{2013, 1, 5}, 58.19, 165.96, 197.05}, {{2013, 1, 6}, 69.99, 163.50, 187.52}, {{2013, 1, 7}, 71.37, 154.21, 175.58}, {{2013, 1, 8}, 72.51, 149.66, 163.25}}; I want a DateListPlot with three graphs, so for a matrix formed by columns 1 and 2, one for columns 1 and 3, and 1 for columns 1 and 4. At the moment I'm using this code: data2 = Transpose[{data[[All, 1]], data[[All, 2]]}]; data3 = Transpose[{data[[All, 1]], data[[All, 3]]}]; data4 = Transpose[{data[[All, 1]], data[[All, 4]]}]; DateListPlot[{data2, data3, data4}, Joined -> True, Filling -> {3 -> {1}}] but I have a hunch that this can be done more efficiently. I don't like the Transpose s in particular. Any ideas? edit (for extra credit) What if I need to multiply the second column by 2, which in my solution is simp...

plotting - How to draw lines between specified dots on ListPlot?

I would like to create a plot where I have unconnected dots and some connected. So far, I have figured out how to draw the dots. My code is the following: ListPlot[{{1, 1}, {2, 2}, {3, 3}, {4, 4}, {1, 4}, {2, 5}, {3, 6}, {4, 7}, {1, 7}, {2, 8}, {3, 9}, {4, 10}, {1, 10}, {2, 11}, {3, 12}, {4,13}, {2.5, 7}}, Ticks -> {{1, 2, 3, 4}, None}, AxesStyle -> Thin, TicksStyle -> Directive[Black, Bold, 12], Mesh -> Full] I have thought using ListLinePlot command, but I don't know how to specify to the command to draw only selected lines between the dots. Do have any suggestions/hints on how to do that? Thank you. Answer One possibility would be to use Epilog with Line : ListPlot[ {{1, 1}, {2, 2}, {3, 3}, {4, 4}, {1, 4}, {2, 5}, {3, 6}, {4, 7}, {1, 7}, {2, 8}, {3, 9}, {4, 10}, {1, 10}, {2, 11}, {3, 12}, {4, 13}, {2.5, 7}}, Ticks -> {{1, 2, 3, 4}, None}, AxesStyle -> Thin, TicksStyle -> Directive[Black, Bold, 12], Mesh -> Full, Epilog -> { Line[ ...

dynamic - How can I make a clickable ArrayPlot that returns input?

I would like to create a dynamic ArrayPlot so that the rectangles, when clicked, provide the input. Can I use ArrayPlot for this? Or is there something else I should have to use? Answer ArrayPlot is much more than just a simple array like Grid : it represents a ranged 2D dataset, and its visualization can be finetuned by options like DataReversed and DataRange . These features make it quite complicated to reproduce the same layout and order with Grid . Here I offer AnnotatedArrayPlot which comes in handy when your dataset is more than just a flat 2D array. The dynamic interface allows highlighting individual cells and possibly interacting with them. AnnotatedArrayPlot works the same way as ArrayPlot and accepts the same options plus Enabled , HighlightCoordinates , HighlightStyle and HighlightElementFunction . data = {{Missing["HasSomeMoreData"], GrayLevel[ 1], {RGBColor[0, 1, 1], RGBColor[0, 0, 1], GrayLevel[1]}, RGBColor[0, 1, 0]}, {GrayLevel[0], GrayLevel...