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Avoid evaluation with HoldForm, ReleaseHold for InputField?

Erdem Uguz
Posted 10 years ago

Hello, I am working on creating a CDF file for a calculation where I do high-precision evaluation of functions such as N[func,40]. I wrote a Module that takes user function and rationalize it, this way I create a function with user input accuracy. (Shown Below). When I don't use an inputfield my module works well but with inputfield I can't prevent it to be evaluated.

enter image description here

As you can see I need to avoid the evaluation so that I can evaluate the function in desired accuracy (number of digits). Any idea how I can do this?

Thank you

Erdem

Panel[DynamicModule[{fun = 2.1 Sin[Pi z/2.1]}, Column[{

    Row[{Style["Function ", 12, Blue, Editable -> False], 
      InputField[HoldForm[Dynamic[fun]], FieldSize -> {55, 3}, 
       BaseStyle -> {12}]}, Spacer[1]]
    , Button[Style["Calculate", 14, Green, Editable -> False], 
     Res = upAC[fun]],
    Row[{Style["Result ", 12, Red, Editable -> False], 
      InputField[Dynamic[Res], FieldSize -> {52, 2}, 
       BaseStyle -> {12}]}, Spacer[5]]
    }],
  Initialization :> (upAC[in_] := 
      Module[{out}, 
       out = If[Accuracy[in] == \[Infinity], in, 
         ReleaseHold[Rationalize[in, 10^-Accuracy[in]]]];
       Return[out]];)
  ]]

Also asked in http://mathematica.stackexchange.com/questions/133362/holdform-releasehold-for-inputfield
POSTED BY: Erdem Uguz
4 Replies
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Erdem Uguz
Erdem Uguz
Posted 10 years ago

It is expected number of digits that is true but is it right? Forget about Sin. When I evaluate fg and fg2 with 40 digits fg2 has the right digits not fg . Because it is already evaluated before setting the accuracy after machine zero the digits are not right. My goal is to avoid that and evaluate fg when I need to evaluate with right digits. 

In[190]:= fg = Pi/2.1;
Print[fg];
fg2 = Pi/(21/10);
Print[fg2];
SetAccuracy[fg, 40]
SetAccuracy[fg2, 40]


During evaluation of In[190]:= 1.4959965017094252

During evaluation of In[190]:= (10 \[Pi])/21

Out[194]= 1.4959965017094252193174952481058426201344

Out[195]= 1.495996501709425351648877801561668040094
POSTED BY: Erdem Uguz
Hans Milton
Hans Milton
Posted 10 years ago

Hi,

Sorry, but I dont fully understand what you want to achieve.

However, if I declare Res as a Dynamic variable, outside of the DynamicModule itself, it returns the expected number of digits after pressing Calculate in the DynamicModule:

enter image description here
POSTED BY: Hans Milton
Hans Milton
Hans Milton
Posted 10 years ago

As an alternative to the answer you already received on stackexchange:

Panel[
  DynamicModule[{fun = HoldForm[2.1 Sin[Pi z/2.1]]},
    Column[{
      Row[{
        Style["Function ", 12, Blue, Editable -> False],
        InputField[Dynamic[fun], FieldSize -> {55, 3}, BaseStyle -> {12}]
      },
      Spacer[1]],
      Button[Style["Calculate", 14, Green, Editable -> False], Res = upAC[ReleaseHold@fun]],
      Row[{
        Style["Result ", 12, Red, Editable -> False],
        InputField[Dynamic[Res], FieldSize -> {52, 2}, BaseStyle -> {12}]
      },
      Spacer[5]]
    }],
    Initialization :>
      (
        upAC[in_] :=
        Module[
          {out},
          out = If[Accuracy[in] == \[Infinity], in, Rationalize[in, 10^-Accuracy[in]]];
          Return[out]
        ];
      )
  ]
]

enter image description here
POSTED BY: Hans Milton
Erdem Uguz
Erdem Uguz
Posted 10 years ago

Thank you but it is not working the way it should. Once you ReleaseHold it will go into the function after it is evaluated. 

In[5]:= N[81692243 /54607242, 40] - N[Pi/(21/10), 40]

Out[5]= -7.0657759444036854756171*10^-17

As you can see the result inside Sin can not anymore be evaluated with more than 16 Digits Accuracy.

POSTED BY: Erdem Uguz
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