On the calculation of the generalizedQ-function via Parl's method (Corresp.)

Parl has previously given error bounds suitable for calculating Marcum's
Q
-function. However, it is shown that additional terms in the error bound are necessary for accurate calculations of the generalized
Q
-function
Q_{m}(\alpha, \beta)
. The values of
m, \alpha
, and
\beta
that result in successful algorithm completion are examined. Numerical results are presented for calculations of the noncentral chi-square distribution and the probability of detection for a classical multiobservation detection problem.