nag_exp_integral (s13aac) Example Program Results
     x           y
   2.000e+00   4.890e-02
   9.000e+00   1.245e-05
  -1.000e+00  -1.895e+00
  -1.000e+03 -1.798e+308
Error from nag_exp_integral (s13aac).
NE_REAL_ARG_LE:
  The evaluation has been abandoned due to the likelihood of overflow.
  The argument x < -x_hi.