pygamm.f

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C*********************************************************************
 
C...PYGAMM
C...Gives ordinary Gamma function Gamma(x) for positive, real arguments;
C...see M. Abramowitz, I. A. Stegun: Handbook of Mathematical Functions
C...(Dover, 1965) 6.1.36.
 
      FUNCTION pygamm(X)
 
C...Double precision and integer declarations.
      IMPLICIT DOUBLE PRECISION(a-h, o-z)
      IMPLICIT INTEGER(i-n)
      INTEGER pyk,pychge,pycomp
C...Local array and data.
      dimension b(8)
      DATA b/-0.577191652d0,0.988205891d0,-0.897056937d0,0.918206857d0,
     &-0.756704078d0,0.482199394d0,-0.193527818d0,0.035868343d0/
 
      nx=int(x)
      dx=x-nx
 
      pygamm=1d0
      dxp=1d0
      DO 100 i=1,8
        dxp=dxp*dx
        pygamm=pygamm+b(i)*dxp
  100 CONTINUE
      IF(x.LT.1d0) THEN
        pygamm=pygamm/x
      ELSE
        DO 110 ix=1,nx-1
          pygamm=(x-ix)*pygamm
  110   CONTINUE
      ENDIF
 
      RETURN
      END