* F07THF Example Program Text * Mark 15 Release. NAG Copyright 1991. * .. Parameters .. INTEGER NIN, NOUT PARAMETER (NIN=5,NOUT=6) INTEGER NMAX, NRHMAX, LDA, LDB, LDX PARAMETER (NMAX=8,NRHMAX=NMAX,LDA=NMAX,LDB=NMAX,LDX=NMAX) CHARACTER TRANS, DIAG PARAMETER (TRANS='N',DIAG='N') * .. Local Scalars .. INTEGER I, IFAIL, INFO, J, N, NRHS CHARACTER UPLO * .. Local Arrays .. DOUBLE PRECISION A(LDA,NMAX), B(LDB,NRHMAX), BERR(NRHMAX), + FERR(NRHMAX), WORK(3*NMAX), X(LDX,NMAX) INTEGER IWORK(NMAX) * .. External Subroutines .. EXTERNAL DTRRFS, DTRTRS, F06QFF, X04CAF * .. Executable Statements .. WRITE (NOUT,*) 'F07THF Example Program Results' * Skip heading in data file READ (NIN,*) READ (NIN,*) N, NRHS IF (N.LE.NMAX .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 READ (NIN,*) ((A(I,J),J=I,N),I=1,N) ELSE IF (UPLO.EQ.'L') THEN READ (NIN,*) ((A(I,J),J=1,I),I=1,N) END IF READ (NIN,*) ((B(I,J),J=1,NRHS),I=1,N) * CALL F06QFF('General',N,NRHS,B,LDB,X,LDX) * * Compute solution in the array X * CALL DTRTRS(UPLO,TRANS,DIAG,N,NRHS,A,LDA,X,LDX,INFO) * * Compute backward errors and estimated bounds on the * forward errors * CALL DTRRFS(UPLO,TRANS,DIAG,N,NRHS,A,LDA,B,LDB,X,LDX,FERR,BERR, + WORK,IWORK,INFO) * * Print solution * WRITE (NOUT,*) IFAIL = 0 CALL X04CAF('General',' ',N,NRHS,X,LDX,'Solution(s)',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 * 99999 FORMAT ((3X,1P,7E11.1)) END