Modified Incomplete Gamma Function [S14] (Algorithm A435) CACM November, 1972 Fullerton, W. modified incomplete Gamma function, incomplete Gamma function, chi-square distribution function, Poisson distribution function 5.13 CA721110 JB January 27, 1978 1:40 PM 2259 5 2259 2259 5 2259 2259 5 2259