pro synodicperiod,coe

  ; coe=1.175
    sdp=25.23                                          ;in days
    x=[-0.554224354,-0.870084408,-0.996202661,-0.900463399,-0.615854357,-0.204564225,0.264551346,0.663428967,0.927203582,0.999533773,0.861360632,0.523007220,0.078724050]
    y=[0.750954032,0.435821632,0.010211775,-0.402947513,-0.730959329,-0.907937549,-0.895938146,-0.699028797,-0.359352296,0.055026800,0.458410238,0.722291855,0.903976706]
    z=[0.325489267,0.188873305,0.004362431,-0.174751924,-0.316952531,-0.395015752,-0.388470635,-0.303102172,-0.155839469,0.023809651,0.198692451,0.334774805,0.391868610]
    vx=[-14501990,-8461598,-390478,7330288,13365541,16625663,16323805,12717728,6473851,-1229256,-8840223,-14858646,-17428145]
    vy=[-8940977,-13941116,-15838038,-14208715,-9663982,-3222311,4068588,10283760,14461160,15704543,13636065,8328533,1238079]
    vz=[-3875321,-6043040,-6865462,-6159132,-4188865,-1396186,1764642,4459151,6270202,6809246,5912498,3611514,537627]
    vx=vx*1.0E-9
    vy=vy*1.0E-9
    vz=vz*1.0E-9
    rse=fltarr(13) & ve=rse & vs=rse & snp=rse
    for i=0,12 do begin
        rse(i)=SQRT(x(i)*x(i)+y(i)*y(i)+z(i)*z(i))
        ve(i)=SQRT(vx(i)*vx(i)+vy(i)*vy(i)+vz(i)*vz(i))   
        vs(i)=rse(i)*2*!pi/sdp                                   ;in AU/day
       ;ve=2*!pi*rse/365.
        snp(i)=sdp+coe*(ve(i)*sdp)/vs(i)
    endfor
    print,'rse:',rse
    print,'ve:',ve
    print,'vs:',vs
    print,'snp:',snp

end