SUBROUTINE GAU2(K,H0,LDH0,H1,LDH1,HB0,HB1,THETA1,THETA2)
C  This routine generates two, antithetic, drawings from the posterior
C  distribution, given a Gaussian prior and Gaussian likelihood.
C  Inputs:
C  K       Order of distribution
C  H0      Prior precision matrix
C  LDH0    Leading dimension of H0
C  H1      Data precision matrix
C  LDH1    Leading dimension of H1
C  HB0     Product of prior precision matrix and mean
C  HB1     Product of data precision matrix and mean
C  Outputs:
C  THETA1  Drawing from postrior
C  THETA2  Antithetic of THETA1
      IMPLICIT REAL*8 (A-H,O-Z)
      PARAMETER(LD=100)
      COMMON/SCRA/V1(LD),V2(LD),A1(LD,LD),A2(LD,LD)
      DIMENSION H0(LDH0,K),H1(LDH1,K),HB0(K),HB1(K),
     1  THETA1(K),THETA2(K)
C  Compute posterior precision
       CALL UMADD(K,K,H0,LDH0,H1,LDH1,A2,LD)
C  Compute posterior mean
      CALL UVADD(K,HB0,HB1,V1)
      CALL DLSLDS(K,A2,LD,V1,V2)
C  Draw realization
      CALL GAU(K,V2,A2,LD,THETA1,THETA2)
      RETURN
      END