I am evaluating a difficult integral of an oscillating function.
f:=k->evalhf(piecewise(k=0,1,k>0,cos(k*(dz))*BK0(k*rho1)/BK0(k*a)));
evalf(Int(f, kmin..kmax, method = _d01akc,epsilon=eps,maxintervals=1000000))
with dz>0 and possibly very large
kmin is Pi/(2*dz)
the number of cycles is nc = ceil((1/2)*kl*dz/Pi) with kl = 91.563
kmax= kmin+nc*2*Pi/dz
Each evaluation of this integral using a call to the NAG routine (_d01akc ) eats up