C         SUBROUTINE TO CALCULATE PARTIAL PRODUCT MATRICES  PAC
C
          SUBROUTINE PRTPRD(IMOD,MODULE)
          COMMON/ACCUM/RAC(3,3,15)
          COMMON/PROD/PAC(3,3,15)
          IF(IMOD.EQ.0)GO TO 100
          DO 69 K=1,3
          DO 69 J=1,3
          SUM=0.
          DO 68 I=1,3
68        SUM=PAC(J,I,IMOD)*RAC(I,K,MODULE)+SUM
69        PAC(J,K,MODULE)=SUM
          GO TO 99
100       DO 101 K=1,3
          DO 101 J=1,3
101       PAC(J,K,MODULE)=RAC(J,K,MODULE)
99        RETURN
          END