coga                    coga: Convolution of independent Gamma
                        Distributions
dcoga                   Convolution of Gamma Distributions (Exact
                        Method).
dcoga2dim               Convolution of Two Gamma Distributions (Exact
                        Method).
dcoga_approx            Convolution of Gamma distribuitons
                        (Approximation Method)
pcoga2dim_diff_shape    Recurrence Identity of Shape Parameter for
                        'pcoga2dim'
