Add graph references
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Abdelrahman Said
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/* -- translated by f2c (version 20240504).
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You must link the resulting object file with libf2c:
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on Microsoft Windows system, link with libf2c.lib;
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on Linux or Unix systems, link with .../path/to/libf2c.a -lm
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or, if you install libf2c.a in a standard place, with -lf2c -lm
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-- in that order, at the end of the command line, as in
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cc *.o -lf2c -lm
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Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
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http://www.netlib.org/f2c/libf2c.zip
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*/
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#include "f2c.h"
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/* Table of constant values */
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static integer c__1 = 1;
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/* -----------------------------------------------------------------------
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\BeginDoc
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\Name: dseigt
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\Description:
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Compute the eigenvalues of the current symmetric tridiagonal matrix
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and the corresponding error bounds given the current residual norm.
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\Usage:
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call dseigt
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( RNORM, N, H, LDH, EIG, BOUNDS, WORKL, IERR )
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\Arguments
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RNORM Double precision scalar. (INPUT)
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RNORM contains the residual norm corresponding to the current
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symmetric tridiagonal matrix H.
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N Integer. (INPUT)
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Size of the symmetric tridiagonal matrix H.
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H Double precision N by 2 array. (INPUT)
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H contains the symmetric tridiagonal matrix with the
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subdiagonal in the first column starting at H(2,1) and the
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main diagonal in second column.
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LDH Integer. (INPUT)
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Leading dimension of H exactly as declared in the calling
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program.
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EIG Double precision array of length N. (OUTPUT)
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On output, EIG contains the N eigenvalues of H possibly
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unsorted. The BOUNDS arrays are returned in the
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same sorted order as EIG.
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BOUNDS Double precision array of length N. (OUTPUT)
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On output, BOUNDS contains the error estimates corresponding
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to the eigenvalues EIG. This is equal to RNORM times the
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last components of the eigenvectors corresponding to the
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eigenvalues in EIG.
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WORKL Double precision work array of length 3*N. (WORKSPACE)
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Private (replicated) array on each PE or array allocated on
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the front end.
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IERR Integer. (OUTPUT)
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Error exit flag from dstqrb.
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\EndDoc
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-----------------------------------------------------------------------
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\BeginLib
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\Local variables:
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xxxxxx real
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\Routines called:
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dstqrb ARPACK routine that computes the eigenvalues and the
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last components of the eigenvectors of a symmetric
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and tridiagonal matrix.
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arscnd ARPACK utility routine for timing.
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dvout ARPACK utility routine that prints vectors.
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dcopy Level 1 BLAS that copies one vector to another.
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\Author
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Danny Sorensen Phuong Vu
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Richard Lehoucq CRPC / Rice University
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Dept. of Computational & Houston, Texas
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Applied Mathematics
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Rice University
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Houston, Texas
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\Revision history:
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xx/xx/92: Version ' 2.4'
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\SCCS Information: @(#)
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FILE: seigt.F SID: 2.4 DATE OF SID: 8/27/96 RELEASE: 2
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\Remarks
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None
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\EndLib
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-----------------------------------------------------------------------
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Subroutine */ int igraphdseigt_(doublereal *rnorm, integer *n, doublereal *h__,
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integer *ldh, doublereal *eig, doublereal *bounds, doublereal *workl,
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integer *ierr)
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{
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/* System generated locals */
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integer h_dim1, h_offset, i__1;
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doublereal d__1;
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/* Local variables */
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integer k;
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real t0, t1;
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extern /* Subroutine */ int igraphdcopy_(integer *, doublereal *, integer *,
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doublereal *, integer *), igraphdvout_(integer *, integer *, doublereal
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*, integer *, char *, ftnlen), igrapharscnd_(real *);
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integer logfil=6, ndigit=-3, mseigt=0;
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extern /* Subroutine */ int igraphdstqrb_(integer *, doublereal *, doublereal *,
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doublereal *, doublereal *, integer *);
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real tseigt=0;
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integer msglvl;
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/* %----------------------------------------------------%
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| Include files for debugging and timing information |
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%----------------------------------------------------%
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%------------------%
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| Scalar Arguments |
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%------------------%
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%-----------------%
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| Array Arguments |
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%-----------------%
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%------------%
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| Parameters |
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%------------%
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%---------------%
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| Local Scalars |
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%---------------%
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%----------------------%
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| External Subroutines |
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%----------------------%
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%-----------------------%
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| Executable Statements |
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%-----------------------%
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%-------------------------------%
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| Initialize timing statistics |
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| & message level for debugging |
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%-------------------------------%
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Parameter adjustments */
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--workl;
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--bounds;
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--eig;
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h_dim1 = *ldh;
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h_offset = 1 + h_dim1;
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h__ -= h_offset;
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/* Function Body */
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igrapharscnd_(&t0);
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msglvl = mseigt;
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if (msglvl > 0) {
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igraphdvout_(&logfil, n, &h__[(h_dim1 << 1) + 1], &ndigit, "_seigt: main d"
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"iagonal of matrix H", (ftnlen)33);
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if (*n > 1) {
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i__1 = *n - 1;
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igraphdvout_(&logfil, &i__1, &h__[h_dim1 + 2], &ndigit, "_seigt: sub d"
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"iagonal of matrix H", (ftnlen)32);
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}
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}
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igraphdcopy_(n, &h__[(h_dim1 << 1) + 1], &c__1, &eig[1], &c__1);
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i__1 = *n - 1;
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igraphdcopy_(&i__1, &h__[h_dim1 + 2], &c__1, &workl[1], &c__1);
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igraphdstqrb_(n, &eig[1], &workl[1], &bounds[1], &workl[*n + 1], ierr);
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if (*ierr != 0) {
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goto L9000;
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}
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if (msglvl > 1) {
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igraphdvout_(&logfil, n, &bounds[1], &ndigit, "_seigt: last row of the eig"
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"envector matrix for H", (ftnlen)48);
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}
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/* %-----------------------------------------------%
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| Finally determine the error bounds associated |
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| with the n Ritz values of H. |
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%-----------------------------------------------% */
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i__1 = *n;
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for (k = 1; k <= i__1; ++k) {
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bounds[k] = *rnorm * (d__1 = bounds[k], abs(d__1));
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/* L30: */
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}
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igrapharscnd_(&t1);
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tseigt += t1 - t0;
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L9000:
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return 0;
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/* %---------------%
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| End of dseigt |
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%---------------% */
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} /* igraphdseigt_ */
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