Can the integral be evaluated without Mathematica?

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In summary, the conversation is discussing the convergence of an integral involving the Riemann zeta function, and the use of integration by parts to evaluate it. The first part of the integral is deemed to be fine, but for large values of x, the function approaches 1/(2x)+o(1/x^2), indicating that it does not converge. The conversation also mentions attempting to evaluate a related integral for a complex value of z.
  • #1
mmzaj
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Does this integral converge !?

[tex] \int_{0}^{\infty}x\frac{d}{dx}\left(\frac{\zeta(x)}{x}+\frac{1}{2x}-\frac{1}{x-1} \right )dx[/tex]
Where [itex]\zeta(x)[/itex] is the Riemann zeta function. Of course, we can integrate by parts to obtain :

[tex]\frac{1}{2}-\int_{0}^{\infty}\left(\frac{\zeta(x)}{x}+\frac{1}{2x}-\frac{1}{x-1}\right) dx [/tex]

Unfortunately, i don't know how to do this integral, and i don't have mathematica, hence the thread !
 
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  • #3


mfb said:
Looks like the first part is fine
But for large x, your function approaches 1/(2x)+o(1/x^2)...

And it doesn't converge . i kinda knew it , thanks . i was trying to evaluate a limiting case of the integral :
[tex] \int_{0}^{\infty}\frac{d}{dx}\left(\frac{\zeta(x)}{x}+\frac{1}{2x}-\frac{1}{x-1} \right )\ln\left(-e^{-zx}\right)dx [/tex]
For [itex] z\in \mathbb{C} [/itex]
 

FAQ: Can the integral be evaluated without Mathematica?

What is an integral?

An integral is a mathematical concept that represents the area under a curve in a graph. It is used to solve problems related to finding the total value of a function over a given range.

How do you determine if an integral converges?

An integral converges if the area under the curve is finite, meaning it does not approach infinity. This can be determined by evaluating the integral using various methods such as the limit comparison test, the ratio test, or the integral test.

What is the difference between a convergent and a divergent integral?

A convergent integral has a finite area under the curve, while a divergent integral has an infinite area. In other words, a convergent integral has a definite solution, while a divergent integral does not.

What is the importance of knowing if an integral converges?

Knowing if an integral converges is important in many areas of mathematics and science, including calculus, physics, and engineering. It allows us to find the total value of a function, which can help us understand and solve real-world problems.

Can an integral converge at some points and diverge at others?

Yes, it is possible for an integral to converge at some points and diverge at others. This is known as a conditionally convergent integral. It occurs when the function being integrated alternates between positive and negative values, resulting in different convergence behaviors at different points.

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