Calculate between [-epsilon,epsilon]

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SUMMARY

The discussion centers on the integration of the equation \(-(p(y)f(y)')' = m^2w(y)f(y)\) with \(p(y) = e^{4ky}(1-4ak^2)\) and \(w = -4ae^{2y}k\delta(y)\) over the interval \([0, \infty)\). The user is uncertain whether to calculate the integral from \(\int^{\epsilon}_0\) or \(\int^{-\epsilon}_{\epsilon}\). The conclusion drawn is that if \(f\) is not continuous at zero, the integrand does not exist at that point, affecting the integration process. The result derived is \(f(+\epsilon) = -\frac{m^2 4ak f(0)}{1-4ak^2}\), referencing equations (3)-(6)...(10) from the paper available at arXiv.

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alejandrito29
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i need to integrate

[tex]-(p(y)f(y)')'=m^2w(y)f(y)[/tex]
where
[tex]p(y)=e^{4ky}(1-4ak^2)[/tex] and [tex]w=-4ae^{2y}k\delta(y)[/tex]

but y between [0,infinity[

¿i calculate between [tex]\int^{epsilon}_0?[/tex] or ¿i calculate between [-epsilon,epsilon]?

but, what is??

[tex]\int^{\epsilon}_0(p(y)f(y)')'dy[/tex]

whit f is not continuous in zero


the result is
[tex]f(+\epsilon)=-\frac{m^24akf(0)}{1-4ak^2}[/tex]
 
Last edited:
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alejandrito29 said:
i need to integrate

[tex]-(p(y)f(y)')'=m^2w(y)f(y)[/tex]
where
[tex]p(y)=e^{4ky}(1-4ak^2)[/tex] and [tex]w=-4ae^{2y}k\delta(y)[/tex]

but y between [0,infinity[

¿i calculate between [tex]\int^{epsilon}_0?[/tex] or ¿i calculate between [-epsilon,epsilon]?
I have no idea what you are talking about. What are yu integrating? If you are talking about the integral above, if it is given as a definite integral, you use whatever limits of integration are given. If it is given as an indefinite integral (anti-derivative) you do not use any limits of integration.

but, what is??

[tex]\int^{\epsilon}_0(p(y)f(y)')'dy[/tex]
By the Fundamental Theorem of Calculus, the integral of the derivative of any function is that function:
[tex]\int^{\epsilon}_0(p(y)f(y)')'dy= p(y)f(y)'[/tex]


whit f is not continuous in zero
If f is not continuous at zero, then it is not differentiable at zero and the integrand above does not exist at 0.


the result is
f(+\epsilon)=-\frac{m^24akf(0)}{1-4ak^2}
Since you haven't actually stated what the problem is, I have no idea whether that is correct or not.
 
Last edited by a moderator:

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