pygamm.F

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      FUNCTION pygamm(X)
 
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.
      dimension b(8)
      DATA b/-0.577191652,0.988205891,-0.897056937,0.918206857,
     &-0.756704078,0.482199394,-0.193527818,0.035868343/
 
      nx=int(x)
      dx=x-nx
 
      pygamm=1.
      dxp=1.
      DO 100 i=1,8
      dxp=dxp*dx
      pygamm=pygamm+b(i)*dxp
  100 CONTINUE
      IF(x.LT.1.) THEN
        pygamm=pygamm/x
      ELSE
        DO 110 ix=1,nx-1
        pygamm=(x-ix)*pygamm
  110   CONTINUE
      ENDIF
 
      RETURN
      END