Tuesday, 24 December 2019

integration - On int10left(inti0nftyfracoperatornamegd(x+y)exp(x+y)dxright)dy, being operatornamegd(u) the Gudermannian function



While I was playing with Wolfram Alpha online calculator, to create double integrals involving negative exponentials and the so-called Gudermannian function, denoted in this post as gd(u), I wondered that should be possible to get the closed-form of 10(0gd(x+y)ex+ydx)dy.
I believe that (1) hasn't a very nice closed-form (I was trying to define integrals involving these functions with a nice closed-form).




Question. Can you justify/calculate the closed-form of (1)? Many thanks.




Answer



I used Wolfram Cloud Sandbox



In[1] := Integrate[Integrate[Gudermannian[x+y]/Exp[x+y],{x,0,Infinity}],{y,0,1}]//Simplify//InputForm
Out[1]//InputForm= 1 - Pi^2/24 - Gudermannian[1]/E + Log[2/(1 + E^2)] - PolyLog[2, -E^2]/2

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