∫ exp(-x) from 0 to INFINITY 
             exact = 1
integ_a_inf: calls = 52
integ_a_inf:     Q = 1.00001
estimated error = 0.000200001
   actual error = 8.16678e-06

∫ exp(-x) from 1 to INFINITY 
              Q = 0.367827
          exact = 0.367879
          calls = 40
estimated error = 0.000136783
   actual error = 5.27095e-05

∫ exp(-x) from 0.5 to INFINITY 
              Q = 0.606536
          exact = 0.606531
          calls = 48
estimated error = 0.000160654
   actual error = 5.66835e-06

∫ 1/x^2 from 0.5 to INFINITY 
              Q = 2
          exact = 2
          calls = 40
estimated error = 0.0003
   actual error = 1.31421e-06

====== integ_ing_b ======

∫ exp(x) from -INFINITY to 1
             exact = 2.71828
integ_inf_b:     Q = 2.7183
integ_inf_b: calls = 76
estimated error = 0.00037183
   actual error = 1.86803e-05

∫ exp(-x^2) from -INFINITY to 1
             exact = 1.63305
integ_inf_b:     Q = 1.63305
integ_inf_b: calls = 116
estimated error = 0.000263305
   actual error = 1.7814e-06