* F07VVF Example Program Text * Mark 15 Release. NAG Copyright 1991. * .. Parameters .. INTEGER NIN, NOUT PARAMETER (NIN=5,NOUT=6) INTEGER NMAX, KDMAX, LDAB, NRHMAX, LDB, LDX PARAMETER (NMAX=8,KDMAX=NMAX,LDAB=KDMAX+1,NRHMAX=NMAX, + LDB=NMAX,LDX=NMAX) CHARACTER TRANS, DIAG PARAMETER (TRANS='N',DIAG='N') * .. Local Scalars .. INTEGER I, IFAIL, INFO, J, KD, N, NRHS CHARACTER UPLO * .. Local Arrays .. COMPLEX *16 AB(LDAB,NMAX), B(LDB,NRHMAX), WORK(2*NMAX), + X(LDX,NMAX) DOUBLE PRECISION BERR(NRHMAX), FERR(NRHMAX), RWORK(NMAX) CHARACTER CLABS(1), RLABS(1) * .. External Subroutines .. EXTERNAL F06TFF, X04DBF, ZTBRFS, ZTBTRS * .. Intrinsic Functions .. INTRINSIC MAX, MIN * .. Executable Statements .. WRITE (NOUT,*) 'F07VVF Example Program Results' * Skip heading in data file READ (NIN,*) READ (NIN,*) N, KD, NRHS IF (N.LE.NMAX .AND. KD.LE.KDMAX .AND. NRHS.LE.NRHMAX) THEN * * Read A and B from data file, and copy B to X * READ (NIN,*) UPLO IF (UPLO.EQ.'U') THEN DO 20 I = 1, N READ (NIN,*) (AB(KD+1+I-J,J),J=I,MIN(N,I+KD)) 20 CONTINUE ELSE IF (UPLO.EQ.'L') THEN DO 40 I = 1, N READ (NIN,*) (AB(1+I-J,J),J=MAX(1,I-KD),I) 40 CONTINUE END IF READ (NIN,*) ((B(I,J),J=1,NRHS),I=1,N) CALL F06TFF('General',N,NRHS,B,LDB,X,LDX) * * Compute solution in the array X * CALL ZTBTRS(UPLO,TRANS,DIAG,N,KD,NRHS,AB,LDAB,X,LDX,INFO) * * Compute backward errors and estimated bounds on the * forward errors * CALL ZTBRFS(UPLO,TRANS,DIAG,N,KD,NRHS,AB,LDAB,B,LDB,X,LDX,FERR, + BERR,WORK,RWORK,INFO) * * Print solution * WRITE (NOUT,*) IFAIL = 0 CALL X04DBF('General',' ',N,NRHS,X,LDX,'Bracketed','F7.4', + 'Solution(s)','Integer',RLABS,'Integer',CLABS,80,0, + IFAIL) WRITE (NOUT,*) WRITE (NOUT,*) 'Backward errors (machine-dependent)' WRITE (NOUT,99999) (BERR(J),J=1,NRHS) WRITE (NOUT,*) + 'Estimated forward error bounds (machine-dependent)' WRITE (NOUT,99999) (FERR(J),J=1,NRHS) END IF STOP * 99999 FORMAT ((5X,1P,4(E11.1,7X))) END