Laplace Transform of Lambert W function











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Does there exist a Laplace transform of the Lambert W function (evaluated at $at$, where $a$ is a constant) that can be expressed in terms of elementary functions and the product log ($W(x)$)?



The Lambert W function is defined as the inverse of $f$ given $f(x) = xe^x$



$W'(x) = W(x)/x(1+W(x))$



$int W(ax) = x(W(ax)−1)+xW(ax)+C$



The Laplace Transform would be the evaluation of the improper integral $int_0^infty e^{-st}W(at)dt$



If such a transform exists, how is it expressed in terms of $s$, and how is it derived?










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  • Of course, the Laplace transform of the Lambert's W function exists. As far as I know, there is no standard mathematic function or combination of a limited number of standard mathematic functions, to express it on a closed form. One have to wait until a new convenient special function be defined and standardized !
    – JJacquelin
    Oct 25 at 7:49

















up vote
2
down vote

favorite












Does there exist a Laplace transform of the Lambert W function (evaluated at $at$, where $a$ is a constant) that can be expressed in terms of elementary functions and the product log ($W(x)$)?



The Lambert W function is defined as the inverse of $f$ given $f(x) = xe^x$



$W'(x) = W(x)/x(1+W(x))$



$int W(ax) = x(W(ax)−1)+xW(ax)+C$



The Laplace Transform would be the evaluation of the improper integral $int_0^infty e^{-st}W(at)dt$



If such a transform exists, how is it expressed in terms of $s$, and how is it derived?










share|cite|improve this question
























  • Of course, the Laplace transform of the Lambert's W function exists. As far as I know, there is no standard mathematic function or combination of a limited number of standard mathematic functions, to express it on a closed form. One have to wait until a new convenient special function be defined and standardized !
    – JJacquelin
    Oct 25 at 7:49















up vote
2
down vote

favorite









up vote
2
down vote

favorite











Does there exist a Laplace transform of the Lambert W function (evaluated at $at$, where $a$ is a constant) that can be expressed in terms of elementary functions and the product log ($W(x)$)?



The Lambert W function is defined as the inverse of $f$ given $f(x) = xe^x$



$W'(x) = W(x)/x(1+W(x))$



$int W(ax) = x(W(ax)−1)+xW(ax)+C$



The Laplace Transform would be the evaluation of the improper integral $int_0^infty e^{-st}W(at)dt$



If such a transform exists, how is it expressed in terms of $s$, and how is it derived?










share|cite|improve this question















Does there exist a Laplace transform of the Lambert W function (evaluated at $at$, where $a$ is a constant) that can be expressed in terms of elementary functions and the product log ($W(x)$)?



The Lambert W function is defined as the inverse of $f$ given $f(x) = xe^x$



$W'(x) = W(x)/x(1+W(x))$



$int W(ax) = x(W(ax)−1)+xW(ax)+C$



The Laplace Transform would be the evaluation of the improper integral $int_0^infty e^{-st}W(at)dt$



If such a transform exists, how is it expressed in terms of $s$, and how is it derived?







integration improper-integrals laplace-transform lambert-w






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edited Oct 25 at 7:08

























asked Oct 25 at 1:32









ThoughtOfGod

348




348












  • Of course, the Laplace transform of the Lambert's W function exists. As far as I know, there is no standard mathematic function or combination of a limited number of standard mathematic functions, to express it on a closed form. One have to wait until a new convenient special function be defined and standardized !
    – JJacquelin
    Oct 25 at 7:49




















  • Of course, the Laplace transform of the Lambert's W function exists. As far as I know, there is no standard mathematic function or combination of a limited number of standard mathematic functions, to express it on a closed form. One have to wait until a new convenient special function be defined and standardized !
    – JJacquelin
    Oct 25 at 7:49


















Of course, the Laplace transform of the Lambert's W function exists. As far as I know, there is no standard mathematic function or combination of a limited number of standard mathematic functions, to express it on a closed form. One have to wait until a new convenient special function be defined and standardized !
– JJacquelin
Oct 25 at 7:49






Of course, the Laplace transform of the Lambert's W function exists. As far as I know, there is no standard mathematic function or combination of a limited number of standard mathematic functions, to express it on a closed form. One have to wait until a new convenient special function be defined and standardized !
– JJacquelin
Oct 25 at 7:49












2 Answers
2






active

oldest

votes

















up vote
4
down vote













I propose to define a new special function, namely LW$(x)$ :
$$text{LW}(x)=int_0^infty W(t)e^{-x:t}dt$$
where W is the Lamber's W function.



In the futur, if this brand new function becomes standard, if it acquires the honorific status of standard special function, if it spread in the literature with a lot of studies of properties, if it becomes familiar, if it is implemented in mathematical softwares, then you could say :



"The Laplace transform of $quad text{W}(ax)quad$ is $quadfrac{1}{a}text{LW}(frac{s}{a})$."



This would be a typical case of special function emergence, exactly as many special functions emerged : https://fr.scribd.com/doc/14623310/Safari-on-the-country-of-the-Special-Functions-Safari-au-pays-des-fonctions-speciales






share|cite|improve this answer





















  • I seem to remember you from before, you posted a scribd document describing the possibility of a special function that is formed from integrating $x^x$: an idea that has had a long, personal, and somewhat dramatic and somewhat miserable, history with me. You suggested that it should be named a "Sophomore's dream function", as a generalization of the "sophomore's dream" integrals. Right?
    – The_Sympathizer
    Oct 25 at 9:26










  • As it turns out that a slightly more general form than the one you presented can actually be used to do this integral, and thus it would be in effect redundant, if one were to use that, to propose an additional one with the first one already proposed. Would you want to see how it works?
    – The_Sympathizer
    Oct 25 at 9:27












  • I cannot understand what you are asking for.
    – JJacquelin
    Oct 25 at 9:38










  • I was pointing out that I found out the integral at hand here is related to something else you (appear to have) worked with earlier.
    – The_Sympathizer
    Oct 25 at 9:52






  • 1




    @ThoughtOfGod. I am afraid that you don't understand my main answer (a bit humoristic). This is normal if you are not familiar with the general use of special functions. In this case, the answer to your question is very simple : The Laplace transform of the Lambert's W function exists but you cannot express it on closed form only with the elementary functions that you know.
    – JJacquelin
    Oct 25 at 10:51


















up vote
0
down vote













Laplace transform LW(s) of Lambert function W(t) is



$$frac {1} {2i} int_{c-iinfty}^{c+iinfty}s^{-1-y}frac {y^{y-1}} {sin {pi y}},dy,{,c in (0,1)}$$



which is Mellin-Barnes integral. This integral converges for all complex s excluding singularities, of course. I cannot express this integral by known "named" functions.






share|cite|improve this answer





















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    2 Answers
    2






    active

    oldest

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    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

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    active

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    up vote
    4
    down vote













    I propose to define a new special function, namely LW$(x)$ :
    $$text{LW}(x)=int_0^infty W(t)e^{-x:t}dt$$
    where W is the Lamber's W function.



    In the futur, if this brand new function becomes standard, if it acquires the honorific status of standard special function, if it spread in the literature with a lot of studies of properties, if it becomes familiar, if it is implemented in mathematical softwares, then you could say :



    "The Laplace transform of $quad text{W}(ax)quad$ is $quadfrac{1}{a}text{LW}(frac{s}{a})$."



    This would be a typical case of special function emergence, exactly as many special functions emerged : https://fr.scribd.com/doc/14623310/Safari-on-the-country-of-the-Special-Functions-Safari-au-pays-des-fonctions-speciales






    share|cite|improve this answer





















    • I seem to remember you from before, you posted a scribd document describing the possibility of a special function that is formed from integrating $x^x$: an idea that has had a long, personal, and somewhat dramatic and somewhat miserable, history with me. You suggested that it should be named a "Sophomore's dream function", as a generalization of the "sophomore's dream" integrals. Right?
      – The_Sympathizer
      Oct 25 at 9:26










    • As it turns out that a slightly more general form than the one you presented can actually be used to do this integral, and thus it would be in effect redundant, if one were to use that, to propose an additional one with the first one already proposed. Would you want to see how it works?
      – The_Sympathizer
      Oct 25 at 9:27












    • I cannot understand what you are asking for.
      – JJacquelin
      Oct 25 at 9:38










    • I was pointing out that I found out the integral at hand here is related to something else you (appear to have) worked with earlier.
      – The_Sympathizer
      Oct 25 at 9:52






    • 1




      @ThoughtOfGod. I am afraid that you don't understand my main answer (a bit humoristic). This is normal if you are not familiar with the general use of special functions. In this case, the answer to your question is very simple : The Laplace transform of the Lambert's W function exists but you cannot express it on closed form only with the elementary functions that you know.
      – JJacquelin
      Oct 25 at 10:51















    up vote
    4
    down vote













    I propose to define a new special function, namely LW$(x)$ :
    $$text{LW}(x)=int_0^infty W(t)e^{-x:t}dt$$
    where W is the Lamber's W function.



    In the futur, if this brand new function becomes standard, if it acquires the honorific status of standard special function, if it spread in the literature with a lot of studies of properties, if it becomes familiar, if it is implemented in mathematical softwares, then you could say :



    "The Laplace transform of $quad text{W}(ax)quad$ is $quadfrac{1}{a}text{LW}(frac{s}{a})$."



    This would be a typical case of special function emergence, exactly as many special functions emerged : https://fr.scribd.com/doc/14623310/Safari-on-the-country-of-the-Special-Functions-Safari-au-pays-des-fonctions-speciales






    share|cite|improve this answer





















    • I seem to remember you from before, you posted a scribd document describing the possibility of a special function that is formed from integrating $x^x$: an idea that has had a long, personal, and somewhat dramatic and somewhat miserable, history with me. You suggested that it should be named a "Sophomore's dream function", as a generalization of the "sophomore's dream" integrals. Right?
      – The_Sympathizer
      Oct 25 at 9:26










    • As it turns out that a slightly more general form than the one you presented can actually be used to do this integral, and thus it would be in effect redundant, if one were to use that, to propose an additional one with the first one already proposed. Would you want to see how it works?
      – The_Sympathizer
      Oct 25 at 9:27












    • I cannot understand what you are asking for.
      – JJacquelin
      Oct 25 at 9:38










    • I was pointing out that I found out the integral at hand here is related to something else you (appear to have) worked with earlier.
      – The_Sympathizer
      Oct 25 at 9:52






    • 1




      @ThoughtOfGod. I am afraid that you don't understand my main answer (a bit humoristic). This is normal if you are not familiar with the general use of special functions. In this case, the answer to your question is very simple : The Laplace transform of the Lambert's W function exists but you cannot express it on closed form only with the elementary functions that you know.
      – JJacquelin
      Oct 25 at 10:51













    up vote
    4
    down vote










    up vote
    4
    down vote









    I propose to define a new special function, namely LW$(x)$ :
    $$text{LW}(x)=int_0^infty W(t)e^{-x:t}dt$$
    where W is the Lamber's W function.



    In the futur, if this brand new function becomes standard, if it acquires the honorific status of standard special function, if it spread in the literature with a lot of studies of properties, if it becomes familiar, if it is implemented in mathematical softwares, then you could say :



    "The Laplace transform of $quad text{W}(ax)quad$ is $quadfrac{1}{a}text{LW}(frac{s}{a})$."



    This would be a typical case of special function emergence, exactly as many special functions emerged : https://fr.scribd.com/doc/14623310/Safari-on-the-country-of-the-Special-Functions-Safari-au-pays-des-fonctions-speciales






    share|cite|improve this answer












    I propose to define a new special function, namely LW$(x)$ :
    $$text{LW}(x)=int_0^infty W(t)e^{-x:t}dt$$
    where W is the Lamber's W function.



    In the futur, if this brand new function becomes standard, if it acquires the honorific status of standard special function, if it spread in the literature with a lot of studies of properties, if it becomes familiar, if it is implemented in mathematical softwares, then you could say :



    "The Laplace transform of $quad text{W}(ax)quad$ is $quadfrac{1}{a}text{LW}(frac{s}{a})$."



    This would be a typical case of special function emergence, exactly as many special functions emerged : https://fr.scribd.com/doc/14623310/Safari-on-the-country-of-the-Special-Functions-Safari-au-pays-des-fonctions-speciales







    share|cite|improve this answer












    share|cite|improve this answer



    share|cite|improve this answer










    answered Oct 25 at 8:27









    JJacquelin

    42.3k21750




    42.3k21750












    • I seem to remember you from before, you posted a scribd document describing the possibility of a special function that is formed from integrating $x^x$: an idea that has had a long, personal, and somewhat dramatic and somewhat miserable, history with me. You suggested that it should be named a "Sophomore's dream function", as a generalization of the "sophomore's dream" integrals. Right?
      – The_Sympathizer
      Oct 25 at 9:26










    • As it turns out that a slightly more general form than the one you presented can actually be used to do this integral, and thus it would be in effect redundant, if one were to use that, to propose an additional one with the first one already proposed. Would you want to see how it works?
      – The_Sympathizer
      Oct 25 at 9:27












    • I cannot understand what you are asking for.
      – JJacquelin
      Oct 25 at 9:38










    • I was pointing out that I found out the integral at hand here is related to something else you (appear to have) worked with earlier.
      – The_Sympathizer
      Oct 25 at 9:52






    • 1




      @ThoughtOfGod. I am afraid that you don't understand my main answer (a bit humoristic). This is normal if you are not familiar with the general use of special functions. In this case, the answer to your question is very simple : The Laplace transform of the Lambert's W function exists but you cannot express it on closed form only with the elementary functions that you know.
      – JJacquelin
      Oct 25 at 10:51


















    • I seem to remember you from before, you posted a scribd document describing the possibility of a special function that is formed from integrating $x^x$: an idea that has had a long, personal, and somewhat dramatic and somewhat miserable, history with me. You suggested that it should be named a "Sophomore's dream function", as a generalization of the "sophomore's dream" integrals. Right?
      – The_Sympathizer
      Oct 25 at 9:26










    • As it turns out that a slightly more general form than the one you presented can actually be used to do this integral, and thus it would be in effect redundant, if one were to use that, to propose an additional one with the first one already proposed. Would you want to see how it works?
      – The_Sympathizer
      Oct 25 at 9:27












    • I cannot understand what you are asking for.
      – JJacquelin
      Oct 25 at 9:38










    • I was pointing out that I found out the integral at hand here is related to something else you (appear to have) worked with earlier.
      – The_Sympathizer
      Oct 25 at 9:52






    • 1




      @ThoughtOfGod. I am afraid that you don't understand my main answer (a bit humoristic). This is normal if you are not familiar with the general use of special functions. In this case, the answer to your question is very simple : The Laplace transform of the Lambert's W function exists but you cannot express it on closed form only with the elementary functions that you know.
      – JJacquelin
      Oct 25 at 10:51
















    I seem to remember you from before, you posted a scribd document describing the possibility of a special function that is formed from integrating $x^x$: an idea that has had a long, personal, and somewhat dramatic and somewhat miserable, history with me. You suggested that it should be named a "Sophomore's dream function", as a generalization of the "sophomore's dream" integrals. Right?
    – The_Sympathizer
    Oct 25 at 9:26




    I seem to remember you from before, you posted a scribd document describing the possibility of a special function that is formed from integrating $x^x$: an idea that has had a long, personal, and somewhat dramatic and somewhat miserable, history with me. You suggested that it should be named a "Sophomore's dream function", as a generalization of the "sophomore's dream" integrals. Right?
    – The_Sympathizer
    Oct 25 at 9:26












    As it turns out that a slightly more general form than the one you presented can actually be used to do this integral, and thus it would be in effect redundant, if one were to use that, to propose an additional one with the first one already proposed. Would you want to see how it works?
    – The_Sympathizer
    Oct 25 at 9:27






    As it turns out that a slightly more general form than the one you presented can actually be used to do this integral, and thus it would be in effect redundant, if one were to use that, to propose an additional one with the first one already proposed. Would you want to see how it works?
    – The_Sympathizer
    Oct 25 at 9:27














    I cannot understand what you are asking for.
    – JJacquelin
    Oct 25 at 9:38




    I cannot understand what you are asking for.
    – JJacquelin
    Oct 25 at 9:38












    I was pointing out that I found out the integral at hand here is related to something else you (appear to have) worked with earlier.
    – The_Sympathizer
    Oct 25 at 9:52




    I was pointing out that I found out the integral at hand here is related to something else you (appear to have) worked with earlier.
    – The_Sympathizer
    Oct 25 at 9:52




    1




    1




    @ThoughtOfGod. I am afraid that you don't understand my main answer (a bit humoristic). This is normal if you are not familiar with the general use of special functions. In this case, the answer to your question is very simple : The Laplace transform of the Lambert's W function exists but you cannot express it on closed form only with the elementary functions that you know.
    – JJacquelin
    Oct 25 at 10:51




    @ThoughtOfGod. I am afraid that you don't understand my main answer (a bit humoristic). This is normal if you are not familiar with the general use of special functions. In this case, the answer to your question is very simple : The Laplace transform of the Lambert's W function exists but you cannot express it on closed form only with the elementary functions that you know.
    – JJacquelin
    Oct 25 at 10:51










    up vote
    0
    down vote













    Laplace transform LW(s) of Lambert function W(t) is



    $$frac {1} {2i} int_{c-iinfty}^{c+iinfty}s^{-1-y}frac {y^{y-1}} {sin {pi y}},dy,{,c in (0,1)}$$



    which is Mellin-Barnes integral. This integral converges for all complex s excluding singularities, of course. I cannot express this integral by known "named" functions.






    share|cite|improve this answer

























      up vote
      0
      down vote













      Laplace transform LW(s) of Lambert function W(t) is



      $$frac {1} {2i} int_{c-iinfty}^{c+iinfty}s^{-1-y}frac {y^{y-1}} {sin {pi y}},dy,{,c in (0,1)}$$



      which is Mellin-Barnes integral. This integral converges for all complex s excluding singularities, of course. I cannot express this integral by known "named" functions.






      share|cite|improve this answer























        up vote
        0
        down vote










        up vote
        0
        down vote









        Laplace transform LW(s) of Lambert function W(t) is



        $$frac {1} {2i} int_{c-iinfty}^{c+iinfty}s^{-1-y}frac {y^{y-1}} {sin {pi y}},dy,{,c in (0,1)}$$



        which is Mellin-Barnes integral. This integral converges for all complex s excluding singularities, of course. I cannot express this integral by known "named" functions.






        share|cite|improve this answer












        Laplace transform LW(s) of Lambert function W(t) is



        $$frac {1} {2i} int_{c-iinfty}^{c+iinfty}s^{-1-y}frac {y^{y-1}} {sin {pi y}},dy,{,c in (0,1)}$$



        which is Mellin-Barnes integral. This integral converges for all complex s excluding singularities, of course. I cannot express this integral by known "named" functions.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Nov 22 at 17:54









        Vojta

        1




        1






























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