* F07JPF Example Program Text * Mark 21 Release. NAG Copyright 2004. * .. Parameters .. INTEGER NIN, NOUT PARAMETER (NIN=5,NOUT=6) INTEGER NMAX PARAMETER (NMAX=8) INTEGER LDB, LDX, NRHSMX PARAMETER (LDB=NMAX,LDX=NMAX,NRHSMX=NMAX) * .. Local Scalars .. DOUBLE PRECISION RCOND INTEGER I, IFAIL, INFO, J, N, NRHS * .. Local Arrays .. COMPLEX *16 B(LDB,NRHSMX), E(NMAX-1), EF(NMAX-1), WORK(NMAX), + X(LDX,NRHSMX) DOUBLE PRECISION BERR(NRHSMX), D(NMAX), DF(NMAX), FERR(NRHSMX), + RWORK(NMAX) CHARACTER CLABS(1), RLABS(1) * .. External Subroutines .. EXTERNAL X04DBF, ZPTSVX * .. Executable Statements .. WRITE (NOUT,*) 'F07JPF Example Program Results' WRITE (NOUT,*) * Skip heading in data file READ (NIN,*) READ (NIN,*) N, NRHS IF (N.LE.NMAX .AND. NRHS.LE.NRHSMX) THEN * * Read the lower bidiagonal part of the tridiagonal matrix A and * the right hand side b from data file * READ (NIN,*) (D(I),I=1,N) READ (NIN,*) (E(I),I=1,N-1) READ (NIN,*) ((B(I,J),J=1,NRHS),I=1,N) * * Solve the equations AX = B for X * CALL ZPTSVX('Not factored',N,NRHS,D,E,DF,EF,B,LDB,X,LDX,RCOND, + FERR,BERR,WORK,RWORK,INFO) * IF ((INFO.EQ.0) .OR. (INFO.EQ.N+1)) THEN * * Print solution, error bounds and condition number * 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,*) WRITE (NOUT,*) + 'Estimated forward error bounds (machine-dependent)' WRITE (NOUT,99999) (FERR(J),J=1,NRHS) WRITE (NOUT,*) WRITE (NOUT,*) 'Estimate of reciprocal condition number' WRITE (NOUT,99999) RCOND * IF (INFO.EQ.N+1) THEN WRITE (NOUT,*) WRITE (NOUT,*) + 'The matrix A is singular to working precision' END IF ELSE WRITE (NOUT,99998) 'The leading minor of order ', INFO, + ' is not positive definite' END IF ELSE WRITE (NOUT,*) 'NMAX and/or NRHSMX too small' END IF STOP * 99999 FORMAT (1X,1P,7E11.1) 99998 FORMAT (1X,A,I3,A) END