kgamma.f File Reference

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Functions/Subroutines
real *8 function	kgamma (x)

Function/Subroutine Documentation

kgamma()

real*8 function kgamma

(

real*8

x

)

Definition at line 25 of file kgamma.f.

References d, d0, and parameter().

Referenced by catmnctcos().

!
      implicit none
      real*8 x
!
      real*8 pi, z, f, t
!
!
      parameter(pi=3.141592653)
!
      if(abs(x).gt.15.d0) then
          z=x
          if(z .le. 0.d0) then
               f=pi/sin(pi*z)
               z=1.d0-z
          endif     
          kgamma=2.506628274d0*exp(-z)*z**(z-0.5d0)*
     *         ((3.47222222222d-3/z+8.3333333133d-2)/z+1.d0)
          if(x .lt. 0.d0) then
               kgamma=f/kgamma
          endif
      else
           f=1.
           z=x
           do while (z .gt. 3.0)
                z=z-1.
                f=f*z
           enddo   
           do while (z .lt. 2.0) 
               f=f*z
               z=z+1.
           enddo    
           z=z-2.0
           t = (((((1.08298598d-2*z - 3.42705226d-3)*z + 7.7549276d-2)*z
     *     + 8.01782477d-2)*z + 4.12102903d-1)*z +4.22766368d-1)* z +
     *          1.0000002d0
           if(x .lt. 2.0d0) f=1.0d0/f
           kgamma=t*f
        endif   

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