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The following code prints the the value of the solution $x(t)$ to an ODE at a user defined time $t_f$. I want the value (0.350232) to appear within the Panel and not below the Panel as the following image. I want to format the Button/Print option to display $x_f=0$.350232 within the Panel. Thanks for your help.

enter image description here

Panel@DynamicModule[{sol, t0 = 0, x0 = 0, xf = 1},
sol = NDSolve[{y'[t] == t^2 + y[t]^2, y[t0] == x0}, y, {t, t0, tf}, 
Method -> "ExplicitRungeKutta"];
x[t_] = y[t] /. First[sol];
Column[{
Row[{Spacer[150], Text["Title"]}],
Row[{
  Control[{{t0, Null, Style[Subscript[t, 0]]}, ImageSize -> 60}], 
  Spacer[10],
  Control[{{x0, Null, Style[Subscript[x, 0]]}, ImageSize -> 60}], 
  Spacer[10], 
  Control[{{tf, Null, Style[Subscript[t, f]]}, ImageSize -> 60}], 
  Spacer[40],
  Button[Style["Evaluate \!\(\*SubscriptBox[\(x\), \(f\)]\)"], 
   Print@Evaluate[x[tf] /. sol]]}]
  }],
  SaveDefinitions -> True]
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1 Answer 1

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4
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You might try something like this. The approach is somewhat different than yours, but I think it gives both cleaner code and a GUI that is easier to use. 

Clear[y]
Panel @
  DynamicModule[{yF, t0 = 0, y0 = 0, tf = 1},
    Dynamic @ 
      Column[
        {Row[{Spacer[150], Text["Title"]}],
         Row[
           {Control[{{t0, t0, Style[Subscript[t, 0]]}, ImageSize -> 60}], 
            Spacer[10],
            Control[{{y0, y0, Style[Subscript[y, 0]]}, ImageSize -> 60}], 
            Spacer[10],
            Control[{{tf, tf, Style[Subscript[t, f]]}, ImageSize -> 60}]],
         Panel[
           yF =
             NDSolveValue[{y'[t] == t^2 + y[t]^2, y[t0] == y0}, y, {t, t0, tf},
               Method -> "ExplicitRungeKutta"];
           Column[
             {Plot[yF[t], {t, t0, tf}, ImageSize -> Medium], 
              yF[tf]}],
             Background -> White]}]]

panel

Of course, if you are determined to use Print, the same approach will still work.

Clear[y]
Panel @
  DynamicModule[{yF, t0 = 0, y0 = 0, tf = 1},
    Dynamic @
      Column[
        {Row[{Spacer[150], Text["Title"]}],
         Row[
          {Control[{{t0, t0, Style[Subscript[t, 0]]}, ImageSize -> 60}], 
           Spacer[10],
           Control[{{y0, y0, Style[Subscript[y, 0]]}, ImageSize -> 60}], 
           Spacer[10],
           Control[{{tf, tf, Style[Subscript[t, f]]}, ImageSize -> 60}], 
           Spacer[40],
           Button["Evaluate ",
             Print[
               yF =
                 NDSolveValue[{y'[t] == t^2 + y[t]^2, y[t0] == y0}, y, {t, t0, tf},
                   Method -> "ExplicitRungeKutta"];
               Column[
                 {Plot[yF[t], {t, t0, tf}, ImageSize -> Medium],
                  yF[tf]},
                 Right]],
             Method -> "Queued"]}]}]]

print

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2
  • $\begingroup$ Thanks for the suggestion. I want a simpler format.and don't need the plot. - just an output like I stated in my question: x_f=value. $\endgroup$
    – Stephen
    Jun 24, 2018 at 19:09
  • $\begingroup$ @Stephen. So simplify one of these two examples so it only puts out yF[tf]. That shouldn't be hard. $\endgroup$
    – m_goldberg
    Jun 25, 2018 at 0:01

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