C LR1L3D    SOURCE    PV090527  23/02/13    21:15:10     11592          
      SUBROUTINE LR1LDP3D(K,G,b,d,s1,s2,s3,Hdp,f1,R1,f2,lr1,ldp,
     # precision3d,log_err)
c      Multiplicateur plastique Rankine1 et Drucker Prager couples
c     (A.Sellier 2021/04/22)
      implicit real*8 (a-h,o-z)
      implicit integer (i-n)
      
      real*8 K,G,b,d,s1,s2,s3,Hdp,f1,R1,f2,lr1,ldp,precision3d
      real*8 CC(2,2),denom
      logical log_err
      log_err=.false.
      
      t3 = R1 ** 2
      t5 = -s2 - s3
      t7 = s2 ** 2
      t8 = 0.3D1 * t7
      t10 = 0.3D1 * s2 * s3
      t11 = s3 ** 2
      t12 = 0.3D1 * t11
      t14 = (0.3D1 * R1 * t5 - t10 + t12 + 0.3D1 * t3 + t8)
      if(t14.ge.0.) then
        t14=sqrt(t14)
      else
        print*,'Pb dans lr1ldp3d t14<0'
        log_err=.true. 
        goto 10        
      end if         
      t15 = 0.1D1 / t14
      t16 = b * K
      t19 = s2 / 0.2D1
      t20 = s3 / 0.2D1
      t27 = s1 ** 2
      t31 = (0.3D1 * s1 * t5 - t10 + t12 + 0.3D1 * t27 + t8)
      if(t31.gt.0.d0) then
        t31=sqrt(t31)
      else
c        print*,'Pb dans lr1ldp3d t14<0'
        log_err=.true. 
        goto 10        
      end if      
      t32 = 0.1D1 / t31
      CC(1,1) = -0.4D1 / 0.3D1 * G - K
      CC(1,2) = -0.4D1 / 0.3D1 * (0.3D1 / 0.4D1 * t14 * t16 + 0.3D1 / 
     # 0.2D1 * (R1 - t19 - t20) * G) * t15
      CC(2,1) = -0.3D1 * (t31 * d * K / 0.3D1 + 0.2D1 / 0.3D1 * (s1 - 
     # t19 - t20) * G) * t32
      CC(2,2) = -0.3D1 * t15 * (t14 * t31 * (d * t16 + Hdp) / 0.3D1 + G 
     # * (t7 + (-R1 / 0.2D1 - s1 / 0.2D1 - s3) * s2 + t11 + s3 * (-R1 - 
     # s1) / 0.2D1 + R1 * s1)) * t32

      denom=CC(1,1) * CC(2,2) - CC(1,2) * CC(2,1)
      
      if(abs(denom).lt.precision3d) then
          log_err=.true.
          goto 10
      else
          lr1 = (CC(1,2) * f2 - CC(2,2) * f1) / denom
          ldp = -(CC(1,1) * f2 - CC(2,1) * f1) / denom      
      end if
      
10    if(log_err.or.lr1.ne.lr1.or.ldp.ne.ldp) then
c        print*,'Pb1 dans lr1l3d'
c        print*,'K,G,b,d,s1,s2,s3,Hdp,f1,R1,f2,lr1,ldp'
c        print*,K,G,b,d,s1,s2,s3,Hdp,f1,R1,f2,lr1,ldp
        lr1=0.d0
        ldp=0.d0
        log_err=.true.
      end if
      
c     attention remplcer s1=R1  dans le gradient de DP( Vdep )    

      return
      end