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












8














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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    8














    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

























      8












      8








      8







      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













      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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      share|cite|improve this question











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      share|cite|improve this question










      asked Nov 13 at 6:33









      Hiraxin

      412




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          7














          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











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          1 Answer
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          active

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          active

          oldest

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          active

          oldest

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          7














          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
















          7














          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














          7












          7








          7






          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



          share|cite|improve this answer








          edited Nov 13 at 9:54

























          answered Nov 13 at 9:47









          Carlo Beenakker

          73.1k9164273




          73.1k9164273












          • 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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