anchor.diff:     vsi = 0.d0
      rhoi = 2.2d3
   
  -   call CIJ_tandon_and_weng(vp,vs,rho,del,c,vpi,vsi,rhoi,CC)
  +   call CIJ_tandon_and_weng(vp,vs,rho,del,c,vpi,vsi,rhoi,CC,rhoout)
      
      write(*,'(a)')  'Output should look like: (x10^7)'
      write(*,'(a)') &
  
positive.code: '    0.0000    0.0000    0.0000    0.0000    0.5574    0.0000',&
  '    0.0000    0.0000    0.0000    0.0000    0.0000    0.5574'
  
     write(*,'(/a)') 'Output: (x10^7)'
     write(*,'(6f10.4)') CC/1.d7
     
  
  end program test_CIJ_tandon_and_weng
negative.code: 
        real(rs), parameter :: big_number = 10.e36 ;      
  
     real(rs)   :: CC(6,6),CCexp(6,6),vp,vs,rho,vpi,vsi,rhoi,c,del,rhoout
     
     vp = 5.8d3
     vs = 3.46d3
  