Elliptic Integral First Kind RF

      x        y        z           actual            rf(x,y,z)
    0.10     0.10     0.10       3.162278e+00       3.162278e+00
    0.00     1.00     2.00       1.311029e+00       1.311029e+00
  100.00   100.00   100.00       1.000000e-01       1.000000e-01