Expressions for the inverse function of f(x) = ln(x)e^x











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Can the inverse of $ ln(x)e^x $ be finitely expressed in terms of the Lambert-W function or any other well-known transcendental functions? It is clear that a closed-form elementary function expression is unreachable.



The reason I ask is in pondering on the links between the inverse Lambert-W and some naturally arising functions of similar forms. Recall that the Lambert-W, a transcendental function, is defined as $ W(xe^x) = x. $



It is natural then to consider the inverse of functions such as $ g(x) = xe^{e^x} $ and those with further exponentiation. With a simple transformation $ z= e^x $ we can reduce $ g(x) $ to the form $ ln(z)e^z $ as originally posed. So the broader question arises: are there tangible algebraic links between the inverses of the set
$$ {xe^x, xe^{e^x},xe^{e^{e^x}}}... $$










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    up vote
    8
    down vote

    favorite












    Can the inverse of $ ln(x)e^x $ be finitely expressed in terms of the Lambert-W function or any other well-known transcendental functions? It is clear that a closed-form elementary function expression is unreachable.



    The reason I ask is in pondering on the links between the inverse Lambert-W and some naturally arising functions of similar forms. Recall that the Lambert-W, a transcendental function, is defined as $ W(xe^x) = x. $



    It is natural then to consider the inverse of functions such as $ g(x) = xe^{e^x} $ and those with further exponentiation. With a simple transformation $ z= e^x $ we can reduce $ g(x) $ to the form $ ln(z)e^z $ as originally posed. So the broader question arises: are there tangible algebraic links between the inverses of the set
    $$ {xe^x, xe^{e^x},xe^{e^{e^x}}}... $$










    share|cite|improve this question







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    Hiraxin is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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      up vote
      8
      down vote

      favorite









      up vote
      8
      down vote

      favorite











      Can the inverse of $ ln(x)e^x $ be finitely expressed in terms of the Lambert-W function or any other well-known transcendental functions? It is clear that a closed-form elementary function expression is unreachable.



      The reason I ask is in pondering on the links between the inverse Lambert-W and some naturally arising functions of similar forms. Recall that the Lambert-W, a transcendental function, is defined as $ W(xe^x) = x. $



      It is natural then to consider the inverse of functions such as $ g(x) = xe^{e^x} $ and those with further exponentiation. With a simple transformation $ z= e^x $ we can reduce $ g(x) $ to the form $ ln(z)e^z $ as originally posed. So the broader question arises: are there tangible algebraic links between the inverses of the set
      $$ {xe^x, xe^{e^x},xe^{e^{e^x}}}... $$










      share|cite|improve this question







      New contributor




      Hiraxin is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      Can the inverse of $ ln(x)e^x $ be finitely expressed in terms of the Lambert-W function or any other well-known transcendental functions? It is clear that a closed-form elementary function expression is unreachable.



      The reason I ask is in pondering on the links between the inverse Lambert-W and some naturally arising functions of similar forms. Recall that the Lambert-W, a transcendental function, is defined as $ W(xe^x) = x. $



      It is natural then to consider the inverse of functions such as $ g(x) = xe^{e^x} $ and those with further exponentiation. With a simple transformation $ z= e^x $ we can reduce $ g(x) $ to the form $ ln(z)e^z $ as originally posed. So the broader question arises: are there tangible algebraic links between the inverses of the set
      $$ {xe^x, xe^{e^x},xe^{e^{e^x}}}... $$







      real-analysis






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      asked Nov 13 at 6:33









      Hiraxin

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          These are so-called hyper-Lambert functions, see
          On some applications of the generalized hyper-Lambert functions.






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          • Thank you much. :)
            – Hiraxin
            Nov 13 at 14:07











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          up vote
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          These are so-called hyper-Lambert functions, see
          On some applications of the generalized hyper-Lambert functions.






          share|cite|improve this answer























          • Thank you much. :)
            – Hiraxin
            Nov 13 at 14:07















          up vote
          7
          down vote













          These are so-called hyper-Lambert functions, see
          On some applications of the generalized hyper-Lambert functions.






          share|cite|improve this answer























          • Thank you much. :)
            – Hiraxin
            Nov 13 at 14:07













          up vote
          7
          down vote










          up vote
          7
          down vote









          These are so-called hyper-Lambert functions, see
          On some applications of the generalized hyper-Lambert functions.






          share|cite|improve this answer














          These are so-called hyper-Lambert functions, see
          On some applications of the generalized hyper-Lambert functions.







          share|cite|improve this answer














          share|cite|improve this answer



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          edited Nov 13 at 9:54

























          answered Nov 13 at 9:47









          Carlo Beenakker

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          71.3k9160267












          • Thank you much. :)
            – Hiraxin
            Nov 13 at 14:07


















          • Thank you much. :)
            – Hiraxin
            Nov 13 at 14:07
















          Thank you much. :)
          – Hiraxin
          Nov 13 at 14:07




          Thank you much. :)
          – Hiraxin
          Nov 13 at 14:07










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