Help taking an integral within a Function I want to plot

My suggestion ...

First, code the function inside the integral. Code it to return to a wave dEAx<-Function fdEAx(G,lambda,T,x). Set the scale on dEAx to large values of -start to +end.

Plot dEAx as a function of x for a fixed value of G (lambda, T). Code a function that will integrate dEAx. Report the last point of that function.

Now, run the sequence

* generate a dEAx(G) curve
* integrate it
* capture the end point of the integration to a new wave iEA(G) for the given G value

Continue above for a range of G of interest.

My approach is dated; I recommend using pen and paper to rewrite the integral.  Start by re-writing the exponential in the numerator as a couple of factors (one of which can come out of the integral).  Then make a change of variable say f=x/RT.  You should now have a simple integrand that you can evaluate at three critical points: x=-INF,0,INF.  The result of this will indicate how to proceed.

A.G.

Dated but timeless AG. :-)