Exploiting the relation between the Ambarzumian-Chandrasekhar H functi
on and the X function of the isotropic and single speed neutron transp
ort an accurate numerical method is presented to evaluate these X and
H functions. The method uses the IMT quadrature scheme. The theoretica
l error estimate is compared with actual errors. (C) 1997 Elsevier Sci
ence B.V.