!          90 IB1 = 1           IB2 = IB1+N       IB3 = IB2+N       IB4 = IB3+N       IB5 = IB4+N       IB6 = IB5+N       IB7 = IB6+N       IPARM(8) = 6*N+2*ITMAX      IF (ISYM.NE.0) IPARM(8) = IPARM(8)+2*ITMAX      IF (NW.GE.IPARM(8)) GO TO 110         IER = 42          IF (LEVEL.GE.0) WRITE (NOUT,100) NW,IPARM(8)  100 FORMAT ('0','*** F A T A L     E R R O R ************'/'0',   &     &   '    CALLED FROM ITPACK ROUTINE SSORCG '/' ',    &     &   '    NOT ENOUGH WORKSPACE AT ',I10/' ','    SET IPARM(8) =',I10&     &   ,' (NW)')      GO TO 390   !       ! ... PERMUTE TO  RED-BLACK SYSTEM IF REQUESTED !         110 NB = IPARM(9)       IF (NB.LT.0) GO TO 170      N3 = 3*N          CALL IVFILL (N3,IWKSP,0)      CALL PRBNDX (N,NB,IA,JA,IWKSP,IWKSP(IB2),LEVEL,NOUT,IER)            IF (IER.EQ.0) GO TO 130       IF (LEVEL.GE.0) WRITE (NOUT,120) IER,NB     120 FORMAT ('0','*** F A T A L     E R R O R ************'/'0',   &     &   '    CALLED FROM ITPACK ROUTINE SSORCG '/' ',    &     &   '    ERROR DETECTED IN SUBROUTINE  PRBNDX'/' ',  &     &   '    WHICH COMPUTES THE RED-BLACK INDEXING'/' ','    IER = ',I5&     &   ,' IPARM(9) = ',I5,' (NB)')        GO TO 390   !       ! ... PERMUTE MATRIX AND RHS!         130 IF (LEVEL.GE.2) WRITE (NOUT,140) NB         140 FORMAT (/10X,'ORDER OF BLACK SUBSYSTEM = ',I5,' (NB)')      CALL PERMAT (N,IA,JA,A,IWKSP,IWKSP(IB3),ISYM,LEVEL,NOUT,IER)        IF (IER.EQ.0) GO TO 160       IF (LEVEL.GE.0) WRITE (NOUT,150) IER        150 FORMAT ('0','*** F A T A L     E R R O R ************'/'0',   &     &   '    CALLED FROM ITPACK ROUTINE SSORCG '/' ',    &     &   '    ERROR DETECTED IN SUBROUTINE  PERMAT'/' ',  &     &   '    WHICH DOES THE RED-BLACK PERMUTATION'/' ','    IER = ',I5)      GO TO 390     160 CALL PERVEC (N,RHS,IWKSP)             CALL PERVEC (N,U,IWKSP) !       ! ... SCALE LINEAR SYSTEM, U, AND RHS BY THE SQUARE ROOT OF THE     ! ... DIAGONAL ELEMENTS.    !         170 CONTINUE          CALL VFILL (IPARM(8),WKSP,0.0D0)      CALL SCAL (N,IA,JA,A,RHS,U,WKSP,LEVEL,NOUT,IER)           IF (IER.EQ.0) GO TO 190       IF (LEVEL.GE.0) WRITE (NOUT,180) IER        180 FORMAT ('0','*** F A T A L     E R R O R ************'/'0',   &     &   '    CALLED FROM ITPACK ROUTINE SSORCG '/' ',    &     &   '    ERROR DETECTED IN SUBROUTINE  SCAL  '/' ',  &     &   '    WHICH SCALES THE SYSTEM   '/' ','    IER = ',I5)            GO TO 390     190 IF (LEVEL.LE.2) GO TO 220             WRITE (NOUT,200)        200 FORMAT (///1X,'IN THE FOLLOWING, RHO AND GAMMA ARE',&     &   ' ACCELERATION PARAMETERS')        WRITE (NOUT,210)        210 FORMAT (1X,'S-PRIME IS AN INITIAL ESTIMATE FOR NEW CME')        220 IF (IPARM(11).NE.0) GO TO 230         TIMI1 = TIMER(DUMMY)  !       ! ... SPECIAL PROCEDURE FOR FULLY ADAPTIVE CASE.!         230 CONTINUE          IF (.NOT.ADAPT) GO TO 250             IF (.NOT.BETADT) GO TO 240            CALL VFILL (N,WKSP(IB1),1.D0)         BETNEW = PBETA(N,IA,JA,A,WKSP(IB1),WKSP(IB2),WKSP(IB3))/      &     &   DBLE(FLOAT(N))           BETAB = DMAX1(BETAB,.25D0,BETNEW)   240 CALL OMEG (0.D0,1)          IS = 0      !       ! ... INITIALIZE FORWARD PSEUDO-RESIDUAL!         250 CALL DCOPY (N,RHS,1,WKSP(IB1),1)      CALL DCOPY (N,U,1,WKSP(IB2),1)        CALL PFSOR (N,IA,JA,A,WKSP(IB2),WKSP(IB1))      CALL VEVMW (N,WKSP(IB2),U)      !       ! ... ITERATION SEQUENCE    !             ITMAX1 = ITMAX+1            DO 270 LOOP = 1,ITMAX1         IN = LOOP-1         IF (MOD(IN,2).EQ.1) GO TO 260!       ! ... CODE FOR THE EVEN ITERATIONS.   !       !     U           = U(IN)       WKSP(IB2) = C(IN) !     WKSP(IB1)   = U(IN-1)     WKSP(IB3) = C(IN-1)       !                CALL ITSRCG (N,IA,JA,A,RHS,U,WKSP(IB1),WKSP(IB2),WKSP(IB3),&     &      WKSP(IB4),WKSP(IB5),WKSP(IB6),WKSP(IB7))      !                IF (HALT) GO TO 300         GO TO 270!       ! ... CODE FOR THE ODD ITERATIONS.    !       !     U           = U(IN-1)     WKSP(IB2) = C(IN-1)       !     WKSP(IB1)   = U(IN)       WKSP(IB3) =C(IN)!         260    CALL ITSRCG (N,IA,JA,A,RHS,WKSP(IB1),U,WKSP(IB3),WKSP(IB2),&     &      WKSP(IB4),WKSP(IB5),WKSP(IB6),WKSP(IB7))      !                IF (HALT) GO TO 300  270 CONTINUE    !       ! ... ITMAX HAS BEEN REACHED!             IF (IPARM(11).NE.0) GO TO 280         TIMI2 = TIMER(DUMMY)        TIME1 = DBLE(TIMI2-TIMI1)         280 IF (LEVEL.GE.1) WRITE (NOUT,290) ITMAX      290 FORMAT ('0','*** W A R N I N G ************'/'0',   &     &   '    IN ITPACK ROUTINE SSORCG'/' ','    FAILURE TO CONVERGE IN'&     &   ,I5,' ITERATIONS')       IER = 43          IF (IPARM(3).EQ.0) RPARM(1) = STPTST            GO TO 330   !       ! ... METHOD HAS CONVERGED  !         300 IF (IPARM(11).NE.0) GO TO 310         TIMI2 = TIMER(DUMMY)        TIME1 = DBLE(TIMI2-TIMI1)         310 IF (LEVEL.GE.1) WRITE (NOUT,320) IN         320 FORMAT (/1X,'SSORCG  HAS CONVERGED IN ',I5,' ITERATIONS')     !       ! ... PUT SOLUTION INTO U IF NOT ALREADY THERE. !         330 CONTINUE          IF (MOD(IN,2).EQ.1) CALL DCOPY (N,WKSP(IB1),1,U,1)  !       ! ... UNSCALE THE MATRIX, SOLUTION, AND RHS VECTORS.      !             CALL UNSCAL (N,IA,JA,A,RHS,U,WKSP)!       ! ... UN-PERMUTE MATRIX,RHS, AND SOLUTION       !             IF (IPARM(9).LT.0) GO TO 360          CALL PERMAT (N,IA,JA,A,IWKSP(IB2),IWKSP(IB3),ISYM,LEVEL,NOUT, &     &   IERPER)        IF (IERPER.EQ.0) GO TO 350            IF (LEVEL.GE.0) WRITE (NOUT,340) IERPER     340 FORMAT ('0','*** F A T A L     E R R O R ************'/'0',   &     &   '    CALLED FROM ITPACK ROUTINE SSORCG '/' ',    &     &   '    ERROR DETECTED IN SUBROUTINE  PERMAT'/' ',  &     &   '    WHICH UNDOES THE RED-BLACK PERMUTATION   '/' ',       &     &   '    IER = ',I5)         IF (IER.EQ.0) IER = IERPER            GO TO 390     350 CALL PERVEC (N,RHS,IWKSP(IB2))        CALL PERVEC (N,U,IWKSP(IB2))    !       ! ... OPTIONAL ERROR ANALYSIS !         360 IDGTS = IPARM(12)           IF (IDGTS.LT.0) GO TO 370             IF (IPARM(2).LE.0) IDGTS = 0          CALL PERROR5 (N,IA,JA,A,RHS,U,WKSP,DIGIT1,DIGIT2,IDGTS)!       ! ... SET RETURN PARAMETERS IN IPARM AND RPARM  !         370 IF (IPARM(11).NE.0) GO TO 380         TIMJ2 = TIMER(DUMMY)        TIME2 = DBLE(TIMJ2-TIMJ1)         380 IPARM(8) = IPARM(8)-2*(ITMAX-IN)      IF (ISYM.NE.0) IPARM(8) = IPARM(8)-2*(ITMAX-IN)           IF (IPARM(3).NE.0) GO TO 390          IPARM(1) = IN       IPARM(9) = NB       RPARM(2) = CME      RPARM(3) = SME      RPARM(5) = OMEGA            RPARM(6) = SPECR            RPARM(7) = BETAB            RPARM(9) = TIME1            RPARM(10) = TIME2           RPARM(11) = DIGIT1          RPARM(12) = DIGIT2    !         390 CONTINUE          IERR = IER        IF (LEVEL.GE.3) CALL ECHALL (N,IA,JA,A,RHS,IPARM,RPARM,2)     !             RETURN            END       SUBROUTINE SSORSI (NN,IA,JA,A,RHS,U,IWKSP,NW,WKSP,IPARM,RPARM,&     &   IERR)    !       !     ITPACK 2C MAIN SUBROUTINE  SSORSI  (SYMMETRIC SUCCESSIVE RELAX- !                                         ATION SEMI-ITERATION)     !     EACH OF THE MAIN SUBROUTINES:   !           JCG, JSI, SOR, SSORCG, SSORSI, RSCG, RSSI     !     CAN BE USED INDEPENDENTLY OF THE OTHERS   !       ! ... FUNCTION:   !       !          THIS SUBROUTINE, SSORSI, DRIVES THE  SYMMETRIC SOR-SI    !          ALGORITHM.       !       ! ... PARAMETER LIST:       !       !          N      INPUT INTEGER.  DIMENSION OF THE MATRIX. (= NN)   !          IA,JA  INPUT INTEGER VECTORS.  THE TWO INTEGER ARRAYS OF !                 THE SPARSE MATRIX REPRESENTATION.       !          A      INPUT D.P. VECTOR.  THE D.P. ARRAY OF THE SPARSE  !                 MATRIX REPRESENTATION.!          RHS    INPUT D.P. VECTOR.  CONTAINS THE RIGHT HAND SIDE  !                 OF THE MATRIX PROBLEM.!          U      INPUT/OUTPUT D.P. VECTOR.  ON INPUT, U CONTAINS THE !                 INITIAL GUESS TO THE SOLUTION. ON OUTPUT, IT CONTAINS !                 THE LATEST ESTIMATE TO THE SOLUTION.    !          IWKSP  INTEGER VECTOR WORKSPACE OF LENGTH 3*N  !          NW     INPUT INTEGER.  LENGTH OF AVAILABLE WKSP.  ON OUTPUT, !                 IPARM(8) IS AMOUNT USED.      !          WKSP   D.P. VECTOR USED FOR WORKING SPACE.  SSORSI       !                 NEEDS THIS TO BE IN LENGTH AT LEAST  5*N!          IPARM  INTEGER VECTOR OF LENGTH 12.  ALLOWS USER TO SPECIFY!                 SOME INTEGER PARAMETERS WHICH AFFECT THE METHOD.  IF!          RPARM  D.P. VECTOR OF LENGTH 12. ALLOWS USER TO SPECIFY SOME !                 D.P. PARAMETERS WHICH AFFECT THE METHOD.!          IER    OUTPUT INTEGER.  ERROR FLAG. (= IERR)   !       ! ... SSORSI SUBPROGRAM REFERENCES:   !       !          FROM ITPACK    BISRCH, CHEBY, CHGSI, DFAULT, ECHALL, ECHOUT, !                         ITERM, TIMER, ITSRSI, IVFILL, OMEG,       !                         OMGSTR, PARSI, PBETA, PERMAT, PERROR5,     !                         PERVEC, PFSOR, PMULT, PRBNDX, PSSOR1,     !                         PSTOP, PVTBV, QSORT, SBELM, SCAL, DCOPY,  !                         DDOT, SUM3, TSTCHG, UNSCAL, VEVPW, VFILL, !                         VOUT, WEVMW !          SYSTEM         DABS, DLOG, DLOG10, DBLE(AMAX0), DMAX1, DBLE(F!                         MOD, DSQRT  !       !     VERSION:  ITPACK 2C (MARCH 1982)!       !     CODE WRITTEN BY:  DAVID KINCAID, ROGER GRIMES, JOHN RESPESS   !                       CENTER FOR NUMERICAL ANALYSIS     !                       UNIVERSITY OF TEXAS     !                       AUSTIN, TX  78712       !                       (512) 471-1242!       !     FOR ADDITIONAL DETAILS ON THE   !          (A) SUBROUTINE SEE TOMS ARTICLE 1982 !          (B) ALGORITHM  SEE CNA REPORT 150    !       !     BASED ON THEORY BY:  DAVID YOUNG, DAVID KINCAID, LOU HAGEMAN  !       !     REFERENCE THE BOOK:  APPLIED ITERATIVE METHODS      !                          L. HAGEMAN, D. YOUNG !                          ACADEMIC PRESS, 1981 !       !     **************************************************  !     *               IMPORTANT NOTE                   *  !     *                                                *  !     *      WHEN INSTALLING ITPACK ROUTINES ON A      *  !     *  DIFFERENT COMPUTER, RESET SOME OF THE VALUES  *  !     *  IN  SUBROUTNE DFAULT.   MOST IMPORTANT ARE    *  !     *                                                *  !     *   DRELPR      MACHINE RELATIVE PRECISION       *  !     *   RPARM(1)    STOPPING CRITERION               *  !     *                                                *  !     *   ALSO CHANGE SYSTEM-DEPENDENT ROUTINE         *  !     *   SECOND USED IN TIMER                         *  !     *                                                *  !     **************************************************  !       !     SPECIFICATIONS FOR ARGUMENTS    !             INTEGER IA(1),JA(1),IWKSP(1),IPARM(12),NN,NW,IERR         DOUBLE PRECISION A(1),RHS(NN),U(NN),WKSP(NW),RPARM(12)!       !     SPECIFICATIONS FOR LOCAL VARIABLES!             INTEGER IB1,IB2,IB3,IB4,IB5,IDGTS,IER,IERPER,ITMAX1,LOOP,N,NB,N3      DOUBLE PRECISION BETNEW,DIGIT1,DIGIT2,PBETA,TEMP,TIME1,TIME2,TOL!       ! *** BEGIN: ITPACK COMMON  !             INTEGER IN,IS,ISYM,ITMAX,LEVEL,NOUT             COMMON /ITCOM1/ IN,IS,ISYM,ITMAX,LEVEL,NOUT !             LOGICAL ADAPT,BETADT,CASEII,HALT,PARTAD         COMMON /ITCOM2/ ADAPT,BETADT,CASEII,HALT,PARTAD     !             DOUBLE PRECISION BDELNM,BETAB,CME,DELNNM,DELSNM,FF,GAMMA,OMEGA,QA,&     &   QT,RHO,RRR,SIGE,SME,SPECR,SPR,DRELPR,STPTST,UDNM,ZETA            COMMON /ITCOM3/ BDELNM,BETAB,CME,DELNNM,DELSNM,FF,GAMMA,OMEGA,QA, &     &   QT,RHO,RRR,SIGE,SME,SPECR,SPR,DRELPR,STPTST,UDNM,ZETA      !       ! *** END  : ITPACK COMMON  !       ! ... VARIABLES IN COMMON BLOCK - ITCOM1!       !     IN     - ITERATION NUMBER       !     ISYM   - SYMMETRIC/NONSYMMETRIC STORAGE FORMAT SWITCH !     IS     - ITERATION NUMBER WHEN PARAMETERS LAST CHANGED!     ITMAX  - MAXIMUM NUMBER OF ITERATIONS ALLOWED       !     LEVEL  - LEVEL OF OUTPUT CONTROL SWITCH   !     NOUT   - OUTPUT UNIT NUMBER     !       ! ... VARIABLES IN COMMON BLOCK - ITCOM2!       !     ADAPT  - FULLY ADAPTIVE PROCEDURE SWITCH  !     BETADT - SWITCH FOR ADAPTIVE DETERMINATION OF BETA  !     CASEII - ADAPTIVE PROCEDURE CASE SWITCH   !     HALT   - STOPPING TEST SWITCH   !     PARTAD - PARTIALLY ADAPTIVE PROCEDURE SWITCH!       ! ... VARIABLES IN COMMON BLOCK - ITCOM3!       !     BDELNM - TWO NORM OF B TIMES DELTA-SUPER-N!     BETAB  - ESTIMATE FOR THE SPECTRAL RADIUS OF LU MATRIX!     CME    - ESTIMATE OF LARGEST EIGENVALUE   !     DELNNM - INNER PRODUCT OF PSEU