00001 subroutine kerr_schild_traceK(x,y,z,traceK)
00002 use phys_constant, only : long
00003 use def_bh_parameter, only : m_kerr
00004 implicit none
00005 real(long) :: traceK
00006 real(long) :: x, y, z, r, lvu(0:3), lvd(0:3), H, gradH(3)
00007 real(long) :: H2, Hp1, H2H1, H21pH, lvugradH, m, a
00008
00009 call kerr_schild_r_lv_home(x,y,z,r,lvu,lvd,H)
00010 call kerr_schild_gradH(x,y,z,r,H,gradH)
00011 m = m_kerr
00012 H2 = H**2 ; Hp1 = 1.0d0+H
00013 H2H1 = 0.5d0*(2.0d0+H)/Hp1**1.5d0
00014 H21pH = H**2/sqrt(Hp1)
00015 lvugradH = lvu(1)*gradH(1)+lvu(2)*gradH(2)+lvu(3)*gradH(3)
00016
00017 traceK = H2H1*lvugradH + H21pH/m
00018
00019 end subroutine kerr_schild_traceK
