Dirac delta function divided by Dirac delta function












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Is the following defined: (Dirac delta function divided by Dirac delta function)



$$f = frac{delta}{delta} = ?$$










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$begingroup$


Is the following defined: (Dirac delta function divided by Dirac delta function)



$$f = frac{delta}{delta} = ?$$










share|cite|improve this question











$endgroup$








  • 2




    $begingroup$
    I have purged all the comments from this post. Please remember to keep comments on topic, and try not to berate other users.
    $endgroup$
    – Alex Becker
    Sep 6 '13 at 22:57










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    @Flybynight Please join me in chat so that we may discuss this further.
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    – Potato
    Sep 6 '13 at 22:58














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$begingroup$


Is the following defined: (Dirac delta function divided by Dirac delta function)



$$f = frac{delta}{delta} = ?$$










share|cite|improve this question











$endgroup$




Is the following defined: (Dirac delta function divided by Dirac delta function)



$$f = frac{delta}{delta} = ?$$







distribution-theory dirac-delta






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edited Jan 15 at 21:10









Qmechanic

5,17711858




5,17711858










asked Sep 6 '13 at 22:09









OSEOSE

95110




95110








  • 2




    $begingroup$
    I have purged all the comments from this post. Please remember to keep comments on topic, and try not to berate other users.
    $endgroup$
    – Alex Becker
    Sep 6 '13 at 22:57










  • $begingroup$
    @Flybynight Please join me in chat so that we may discuss this further.
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    – Potato
    Sep 6 '13 at 22:58














  • 2




    $begingroup$
    I have purged all the comments from this post. Please remember to keep comments on topic, and try not to berate other users.
    $endgroup$
    – Alex Becker
    Sep 6 '13 at 22:57










  • $begingroup$
    @Flybynight Please join me in chat so that we may discuss this further.
    $endgroup$
    – Potato
    Sep 6 '13 at 22:58








2




2




$begingroup$
I have purged all the comments from this post. Please remember to keep comments on topic, and try not to berate other users.
$endgroup$
– Alex Becker
Sep 6 '13 at 22:57




$begingroup$
I have purged all the comments from this post. Please remember to keep comments on topic, and try not to berate other users.
$endgroup$
– Alex Becker
Sep 6 '13 at 22:57












$begingroup$
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– Potato
Sep 6 '13 at 22:58




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2 Answers
2






active

oldest

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3












$begingroup$

I don't know if the following is what you are looking for, but: To give the division a sense, what you can do is look for functions $phi in mathcal E^0(mathbb R)$ (that is continuous functions $mathbb R to mathbb R$ that fulfill $phi delta = delta$. As for any $psi in mathcal D(mathbb R)$ we have $$(phi delta)(psi) =delta(phipsi) = phi(0)psi(0) = phi(0)delta(psi), $$
that is $phi delta = phi(0)delta$, so we have $$phi delta = delta iff phi(0) = 1. $$






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  • $begingroup$
    what is D(R)?
    $endgroup$
    – user114766
    Oct 17 '17 at 14:52



















0












$begingroup$

Remember $delta$ is 'operationally' defined by its effect under integration. So $delta$/$delta$ needs more context, for example, like



($delta$(x-y),f(x))/($delta$(x-y),g(x)),



where (.,.) is the inner product, before the question can be answered. In this case $delta$/$delta$ = 1 only if f(y)=g(y). Otherwise the results could be one of many other things.






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    2 Answers
    2






    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    3












    $begingroup$

    I don't know if the following is what you are looking for, but: To give the division a sense, what you can do is look for functions $phi in mathcal E^0(mathbb R)$ (that is continuous functions $mathbb R to mathbb R$ that fulfill $phi delta = delta$. As for any $psi in mathcal D(mathbb R)$ we have $$(phi delta)(psi) =delta(phipsi) = phi(0)psi(0) = phi(0)delta(psi), $$
    that is $phi delta = phi(0)delta$, so we have $$phi delta = delta iff phi(0) = 1. $$






    share|cite|improve this answer









    $endgroup$













    • $begingroup$
      what is D(R)?
      $endgroup$
      – user114766
      Oct 17 '17 at 14:52
















    3












    $begingroup$

    I don't know if the following is what you are looking for, but: To give the division a sense, what you can do is look for functions $phi in mathcal E^0(mathbb R)$ (that is continuous functions $mathbb R to mathbb R$ that fulfill $phi delta = delta$. As for any $psi in mathcal D(mathbb R)$ we have $$(phi delta)(psi) =delta(phipsi) = phi(0)psi(0) = phi(0)delta(psi), $$
    that is $phi delta = phi(0)delta$, so we have $$phi delta = delta iff phi(0) = 1. $$






    share|cite|improve this answer









    $endgroup$













    • $begingroup$
      what is D(R)?
      $endgroup$
      – user114766
      Oct 17 '17 at 14:52














    3












    3








    3





    $begingroup$

    I don't know if the following is what you are looking for, but: To give the division a sense, what you can do is look for functions $phi in mathcal E^0(mathbb R)$ (that is continuous functions $mathbb R to mathbb R$ that fulfill $phi delta = delta$. As for any $psi in mathcal D(mathbb R)$ we have $$(phi delta)(psi) =delta(phipsi) = phi(0)psi(0) = phi(0)delta(psi), $$
    that is $phi delta = phi(0)delta$, so we have $$phi delta = delta iff phi(0) = 1. $$






    share|cite|improve this answer









    $endgroup$



    I don't know if the following is what you are looking for, but: To give the division a sense, what you can do is look for functions $phi in mathcal E^0(mathbb R)$ (that is continuous functions $mathbb R to mathbb R$ that fulfill $phi delta = delta$. As for any $psi in mathcal D(mathbb R)$ we have $$(phi delta)(psi) =delta(phipsi) = phi(0)psi(0) = phi(0)delta(psi), $$
    that is $phi delta = phi(0)delta$, so we have $$phi delta = delta iff phi(0) = 1. $$







    share|cite|improve this answer












    share|cite|improve this answer



    share|cite|improve this answer










    answered Sep 6 '13 at 22:39









    martinimartini

    70.8k45991




    70.8k45991












    • $begingroup$
      what is D(R)?
      $endgroup$
      – user114766
      Oct 17 '17 at 14:52


















    • $begingroup$
      what is D(R)?
      $endgroup$
      – user114766
      Oct 17 '17 at 14:52
















    $begingroup$
    what is D(R)?
    $endgroup$
    – user114766
    Oct 17 '17 at 14:52




    $begingroup$
    what is D(R)?
    $endgroup$
    – user114766
    Oct 17 '17 at 14:52











    0












    $begingroup$

    Remember $delta$ is 'operationally' defined by its effect under integration. So $delta$/$delta$ needs more context, for example, like



    ($delta$(x-y),f(x))/($delta$(x-y),g(x)),



    where (.,.) is the inner product, before the question can be answered. In this case $delta$/$delta$ = 1 only if f(y)=g(y). Otherwise the results could be one of many other things.






    share|cite|improve this answer









    $endgroup$


















      0












      $begingroup$

      Remember $delta$ is 'operationally' defined by its effect under integration. So $delta$/$delta$ needs more context, for example, like



      ($delta$(x-y),f(x))/($delta$(x-y),g(x)),



      where (.,.) is the inner product, before the question can be answered. In this case $delta$/$delta$ = 1 only if f(y)=g(y). Otherwise the results could be one of many other things.






      share|cite|improve this answer









      $endgroup$
















        0












        0








        0





        $begingroup$

        Remember $delta$ is 'operationally' defined by its effect under integration. So $delta$/$delta$ needs more context, for example, like



        ($delta$(x-y),f(x))/($delta$(x-y),g(x)),



        where (.,.) is the inner product, before the question can be answered. In this case $delta$/$delta$ = 1 only if f(y)=g(y). Otherwise the results could be one of many other things.






        share|cite|improve this answer









        $endgroup$



        Remember $delta$ is 'operationally' defined by its effect under integration. So $delta$/$delta$ needs more context, for example, like



        ($delta$(x-y),f(x))/($delta$(x-y),g(x)),



        where (.,.) is the inner product, before the question can be answered. In this case $delta$/$delta$ = 1 only if f(y)=g(y). Otherwise the results could be one of many other things.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered May 4 '14 at 15:41









        user45664user45664

        266213




        266213






























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