QUAD:
  C version

  Estimate the integral of f(x) from A to B.
  f(x) = 50 / ( pi * ( 2500 * x * x + 1 ) ).
  A = 0.000000
  B = 10.000000
  Exact integral is 0.49936338107645674464...

  Estimate = 0.499442
  Error    = 7.907843e-05
  W time   = 0.010932
  FLOPS    = 6000000
  MFLOPS   = 548.847414