TAN METHOD APPROXIMATION OF SOME INTEGRALS RELATED TO RADIATION-FIELDPROBLEMS

A more general and unified form of the Hubbell rectangular source inte gral is defined as H[(a,b,p,lambda,mu,nu)(alpha,beta,gamma)] = integra l(0)(b) x(lambda)(x(2) + p)(nu) (1 - x(2)/b(2))(mu) F (alpha,beta,gamm a; - a(2)/x(2) + p) dx subject to gamma > beta > 0; a, b, p > 0; lambd a, mu > -1. Special cases of this integral occur in some radiation fie ld problems. Under certain restrictions, H may be expressed in terms o f Appell's double hypergeometric functions F-2 and F-4. Tau method app roximations of the Gauss hypergeometric function F-2(1) are employed i n the evaluation of this integral, and upper bound estimates on the Ta u error are given.