Search All of the Math Forum:
Views expressed in these public forums are not endorsed by
Drexel University or The Math Forum.



An analytical solution to an integral not currently in Mathematica?
Posted:
Jul 14, 2013 1:44 AM


Question: Integral dx of 1/sqrt(Log[x] + a*x + b) (sorry if my notation is off; I just used the online integrator and don't have Mathematica proper, http://integrals.wolfram.com/index.jsp?expr=1%2Fsqrt%28Log%5Bx%5D+%2B+a*x+%2B+b%29) (the online integrator returned this as of the time of writing this (20130713): "Mathematica could not find a formula for your integral. Most likely this means that no formula exists." )
Another system's unconfirmed answer (in that notation; sorry) (version 5.27.0): sqrt(%pi)*%i*%e^(a*xb)*erf(%i*sqrt(log(x)+a*x+b))
Strangely, the other system only produces this result when given, say, x(t) in all places for x (including variable of integration).
I can't seem to get the other system to verify its result symbolically, but when I try random numerical sampling, it does seem to agree, albeit horribly plagued by floating point errors for large x.
Can anyone offer insight, or possibly prove it's correctness or incorrectness? :)
(P.S. I just joined this group, so apologies if it's the wrong one or I'm not following guidelines)



