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Mathematica: output an expression without evaluating it first 
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#1
Feb2013, 06:28 PM

P: 120

Greetings,
I recently discovered Mathematica's Format function, and it has been of great use to me. However, there is one thing that I want to use it to do, that I have yet to be able to. I could do this easily, though, if there is some Mathematica function that works as follows... If I put a semicolon after inputting something in Mathematica, it evaluates what I input without outputting the result. The function that I am looking for is sort of the inverse of this. I will call the function DoNotEvaluate[] for the rest of this post. Some simple input and output examples for the function that I am looking for would be... Input: DoNotEvaluate[Sqrt[4]] Output: Sqrt[4]  note that the output is not 2. Input: DoNotEvaluate[Sqrt[2*2]] Output: Sqrt[2*2]  note that the output is neither Sqrt[4] or 2. Input: x=2*2; DoNotEvaluate[Sqrt[x]] Output: Sqrt[4] Does anyone know of a Mathematica function, or other Mathematica technique, that does what my madeup DoNotEvaluate[] function does? Thanks for any help you can give. HJ Farnsworth 


#2
Feb2013, 07:53 PM

P: 1,029

Perhaps one of these or some combination?
http://reference.wolfram.com/mathema.../HoldForm.html http://reference.wolfram.com/mathema...f/HoldAll.html http://reference.wolfram.com/mathema...dComplete.html http://reference.wolfram.com/mathema...lComplete.html http://reference.wolfram.com/mathema...evaluated.html There are even more of these, but I don't think the process of shielding some things from evaluation while getting other things done has been explained in any documentation that I have seen. 


#3
Feb2013, 09:28 PM

P: 120

Thank you for the very quick and complete response. That's pretty much what I wanted.
HJ Farnsworth 


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