function DLDR(ALPHA,BETA)
      A=[0.0050    0.0070    0.0130    0.0180    0.0150    0.0210    0.0230
         0.0170    0.0160    0.0130    0.0150    0.0140    0.0110    0.0100
         0.0140    0.0140    0.0110    0.0150    0.0130    0.0100    0.0110
         0.0100    0.0140    0.0120    0.0140    0.0130    0.0110    0.0110
        -0.0050    0.0130    0.0110    0.0140    0.0120    0.0100    0.0110
         0.0090    0.0090    0.0090    0.0140    0.0110    0.0090    0.0100
         0.0190    0.0120    0.0080    0.0140    0.0110    0.0080    0.0080
         0.0050    0.0050    0.0050    0.0150    0.0100    0.0100    0.0100
              0         0   -0.0020    0.0130    0.0080    0.0060    0.0060
        -0.0050    0.0040    0.0050    0.0110    0.0080    0.0050    0.0140
        -0.0110    0.0090    0.0030    0.0060    0.0070         0    0.0200
         0.0080    0.0070    0.0050    0.0010    0.0030    0.0010         0]
      #
      S= 0.2 * ALPHA
      K= floor(S)+3
      if(K <= 1)
            K= 2
      end
      if(K >=  12)
            K=  11
      end
      DA= S - K +3
      L = K + fix( 1.1*sign(DA) )
      #
      S= 0.1 * BETA
      M= floor(S)+4
      if(M <= 1)
            M= 2
      end
      if(M >=  7)
            M=  6
      end
      DB= S - M + 4
      N= M + fix( 1.1*sign(DB) )
      #
      K=convert(Int64, K)
      L=convert(Int64, L)
      M=convert(Int64, M)
      N=convert(Int64, N)
      T= A[K,M]
      U= A[K,N]
      V= T + abs(DA) * (A[L,M] - T)
      W= U + abs(DA) * (A[L,N] - U)
      return dldrv = V + (W-V)  * abs(DB)
end
