# dgami.f

          DOUBLE PRECISION FUNCTION DGAMI (A, X)
    C***BEGIN PROLOGUE  DGAMI
    C***PURPOSE  Evaluate the incomplete Gamma function.
    C***LIBRARY   SLATEC (FNLIB)
    C***CATEGORY  C7E
    C***TYPE      DOUBLE PRECISION (GAMI-S, DGAMI-D)
    C***KEYWORDS  FNLIB, INCOMPLETE GAMMA FUNCTION, SPECIAL FUNCTIONS
    C***AUTHOR  Fullerton, W., (LANL)
    C***DESCRIPTION
    C
    C Evaluate the incomplete gamma function defined by
    C
    C DGAMI = integral from T = 0 to X of EXP(-T) * T**(A-1.0) .
    C
    C DGAMI is evaluated for positive values of A and non-negative values
    C of X.  A slight deterioration of 2 or 3 digits accuracy will occur
    C when DGAMI is very large or very small, because logarithmic variables
    C are used.  The function and both arguments are double precision.
    C
    C***REFERENCES  (NONE)
    C***ROUTINES CALLED  DGAMIT, DLNGAM, XERMSG
    C***REVISION HISTORY  (YYMMDD)
    C   770701  DATE WRITTEN
    C   890531  Changed all specific intrinsics to generic.  (WRB)
    C   890531  REVISION DATE from Version 3.2
    C   891214  Prologue converted to Version 4.0 format.  (BAB)
    C   900315  CALLs to XERROR changed to CALLs to XERMSG.  (THJ)
    C***END PROLOGUE  DGAMI