#Exponential integral

22 messages · Page 1 of 1 (latest)

sharp wedge
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I want to understand how to calculate the integrals in the picture. gamma is the Euler Macheroni constant and corresponds to the integral from 0 to infinity of exp(-u) log(u) du

hollow moss
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So the issue is the extra u factor? If so, I think you can just do integration by parts

sharp wedge
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the lower limits leads to blowing up the log, therefore I can not do partial integration

trim raven
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nah partial doesn't really work, we need something beautiful for this

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I'm trying feynmans rn

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see where i can get

trim raven
sharp wedge
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Feynman works thank you!!

trim raven
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BRO i think i found something incredible rn with this

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maybe you did the same idea

sharp wedge
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whats so incredible about it?

trim raven
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digamma

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just cool

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idk

sharp wedge
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So I did e^(alpha u ) for Feynman, I guess you did sth else to obtain the digamma

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Can you share?

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What I found fun is that this implies that exp(-u) (u-1) log(u) is a probability density

trim raven
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ahh this is gorgeous

sharp wedge
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nice so much unrevealed

sharp wedge
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Yes more generally up to a prefactor exp(-u) (u^k- k!) log(u) yields a density