The definite integral is numerically evaluated using integrate
after a variables transformation resulting in the integration range from 0 to 1
instead of the semi-infinite original range.
This may result in higher precision and better numerical stability.
The arguments to the function must be scalars. No vectors allowed.
References
Owen DB. A special case of a bivariate non-central t-distribution. Biometrika. 1965;52(3/4):437--46. tools:::Rd_expr_doi("10.2307/2333696")
Chou YM. A bivariate noncentral T-distibution with applications. Commun Stat Theory Methods. 1992;21(12):3427--62. tools:::Rd_expr_doi("10.1080/03610929208830988")
# This function is mainly intended for internal use.OwensQ(10, 2.5, 5, 0, 2)
#should give [1] 9.388137e-06 OwensQ(10, -2.5, -5, 0, 2)
#should give [1] 0.05264363