I want to use Needs to download the QuickReIm package to simplify the complex conjugation, but I keep getting errors:

here is the Command:


and here are the errors:

Get::noopen: Cannot open QuickReIm`.
Needs::nocont: Context QuickReIm` was not created when Needs was evaluated.

Do you know the reason? Where can I find different packages and their uses?

  • 1
    $\begingroup$ Is it in your Applications folder? $\endgroup$ Dec 28, 2019 at 1:13
  • 3
    $\begingroup$ Needs does not download anything (please check its documentation). What it does is it loads a package, provided that that package is installed. Downloading the package and installing it is something you need to do yourself before the package can be used. "QuickReIm" is not a standard package. If you have a question about it, you should clarify where one can get this package. $\endgroup$
    – Szabolcs
    Dec 28, 2019 at 11:20

1 Answer 1


Not sure about the package you're referring to, but after a quick search I found Quantum Methods with Mathematica (result 5) which gives the source code for their version of the QuickReIm package as

protected = Unprotect[Re, Im, Conjugate]
Conjugate[expr_] := expr /. Complex[x_, y_] :> x - I y
Re[expr_] := Expand[(expr + Conjugate[expr])/2]
Im[expr_] := Expand[(expr - Conjugate[expr])/(2 I)]

And then Needs["QuickReIm`"] evaluates without error.


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