--------------
pseudo-random, N=8000
result	=1.34466
exact	=1.3932
estimated error	=0.0314833
actual error	=-0.0485445
--------------
quasi-random, N=8000
result	=1.37987
exact	=1.3932
estimated error	=0.0418468
actual error	=-0.013334
--------------
stratified, N=8000
result	=1.40677
exact	=1.3932
estimated error	=0.0988263
actual error	=0.0135658