bessel.FF

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c bessel.FF:	Compute Bessel function Jn(z) for n=0,1,2
c Reivsion History
c	03/05/1996  Lupei Zhu   Initial coding.
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      subroutine besselFn(z, aj0, aj1, aj2)
	IMPLICIT NONE
        real z, aj0, aj1, aj2
#ifdef __SUNPRO_F77
	real*8 j0,j1,jn, zz
	EXTERNAL j0,j1,jn               !$pragma C(j0,j1,jn)
	zz = z
	aj0 = j0(%val(zz))
	aj1 = j1(%val(zz))
	aj2 = jn(%val(2),%val(zz))
#elif __GNUC__
	aj0 = BesJ0(z)
	aj1 = BesJ1(z)
	aj2 = BesJN(2,z)
#else
c#warning "no intrinsic Bessel functions found, use it approximation"
        real phi, pi
        pi = 3.1415926535
	phi = z-0.25*pi
	pi = 1./sqrt(0.5*pi*z)
	aj0 = cos(phi)*pi
	aj1 = sin(phi)*pi
	aj2 =-aj0
#endif
        return
      end