∫_0^1 Sqrt(x) dx, acc=0.001 eps=0.001
result=0.666797251934221, calls=40
exact =0.666666666666667
tilerance       =0.00166679725193422
estimated error =0.000307101544092892
actual error    =0.000130585267554051
test passed :)

∫_0^1 4*Sqrt(1-(1-x)²) dx, acc=0.001 eps=0.001
result=3.14172949475203, calls=56
exact =3.14159265358979
tilerance       =0.00414172949475203
estimated error =0.00109016733074966
actual error    =0.000136841162238888
test passed :)