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Algorithm 421: complex gamma function with error control [S14]


This Fortran program computes either the gamma function or the loggamma function of a complex variable in double precision. In addition, it provides an error estimate of the computed answer. The calling sequences are: CALL CDLGAM (Z, W, E, 0) for the loggamma, and CALL CDLGAM (Z, W, E, 1) for the gamma, where Z is the double precision complex argument, W is the answer of the same type, and E is a single precision real variable. Before the call, the value of E is an estimate of the error in Z, and after the call, it is an estimate of the error in W.

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