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Inside a Manipulate, I'd like one of the controls to be an InputField and to allow the input entered to be in traditional form. Is this possible?

For example, in the output from

  Manipulate[func /. x -> val,
     {{val, 0, "x"}}, {{func, x, "f(x)"}},
     ControlType -> InputField]

I'd like to be able to type, say, cos(x) in the second input field and have it interpreted, of course, as Cos[x].

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    $\begingroup$ related 26983 $\endgroup$
    – Kuba
    Commented Mar 2, 2015 at 14:48

2 Answers 2

Reset to default
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Manipulate[ToExpression[func, TraditionalForm] /. x -> val, {{val, Pi, "x"}, InputField},
 {{func, "", "f(x)"}, InputField[##, String] &}]

enter image description here

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  • $\begingroup$ Should I be able to surmise such an answer from the documentation? $\endgroup$
    – murray
    Commented Mar 2, 2015 at 19:43
  • $\begingroup$ That's an interesting mathematical value, resulting from $\sin(\pi/5) = \sqrt{(5-\sqrt{5})/8}$. $\endgroup$
    – murray
    Commented Mar 2, 2015 at 19:48
  • $\begingroup$ @murray, thank you for the Accept. Re documentation, the key piece is from TraditionalForm >> Details and Options. We can get the uninteresting values using Manipulate[N@ToExpression[func, ...] or Manipulate[1. ToExpression[func, ...]:) $\endgroup$
    – kglr
    Commented Mar 2, 2015 at 20:03
  • $\begingroup$ The ToExpression[..., TraditionalForm] part I already knew about. What I did not know was the legality of a control of type {{expr, default, "label"}, InputField[#, String]&}. So applying such a ToExpression construct to the input read didn't occur to me. Of course this did appear in mathematica.stackexchange.com/questions/26983/…. $\endgroup$
    – murray
    Commented Mar 2, 2015 at 20:15
  • $\begingroup$ murray, InputField[##, String, options]& is a special case of the general syntax for Manipulate controls {{u, init,label}, controlfunction[##, options]&}. A reference is in Advanced Manipulate Functionality >> Custom Control Appearances. $\endgroup$
    – kglr
    Commented Mar 2, 2015 at 20:51
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The accepted answer uses a String type InputField, so that you can't enter 2D input. The following Manipulate version allows 2D input:

Manipulate[
    ToExpression[func, TraditionalForm] /. {Null->"", x->val},
    {{val,Pi,"x"}, InputField},
    {{func, Null, "f(x)"}, TraditionalForm@InputField[Dynamic[func],Boxes]&}
]

Here is an animation:

enter image description here

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