--- rpl/lapack/lapack/dlarrb.f	2011/11/21 22:19:34	1.9
+++ rpl/lapack/lapack/dlarrb.f	2023/08/07 08:38:57	1.20
@@ -1,19 +1,19 @@
-*> \brief \b DLARRB
+*> \brief \b DLARRB provides limited bisection to locate eigenvalues for more accuracy.
 *
 *  =========== DOCUMENTATION ===========
 *
-* Online html documentation available at 
-*            http://www.netlib.org/lapack/explore-html/ 
+* Online html documentation available at
+*            http://www.netlib.org/lapack/explore-html/
 *
 *> \htmlonly
-*> Download DLARRB + dependencies 
-*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlarrb.f"> 
-*> [TGZ]</a> 
-*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlarrb.f"> 
-*> [ZIP]</a> 
-*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlarrb.f"> 
+*> Download DLARRB + dependencies
+*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlarrb.f">
+*> [TGZ]</a>
+*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlarrb.f">
+*> [ZIP]</a>
+*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlarrb.f">
 *> [TXT]</a>
-*> \endhtmlonly 
+*> \endhtmlonly
 *
 *  Definition:
 *  ===========
@@ -21,7 +21,7 @@
 *       SUBROUTINE DLARRB( N, D, LLD, IFIRST, ILAST, RTOL1,
 *                          RTOL2, OFFSET, W, WGAP, WERR, WORK, IWORK,
 *                          PIVMIN, SPDIAM, TWIST, INFO )
-* 
+*
 *       .. Scalar Arguments ..
 *       INTEGER            IFIRST, ILAST, INFO, N, OFFSET, TWIST
 *       DOUBLE PRECISION   PIVMIN, RTOL1, RTOL2, SPDIAM
@@ -31,7 +31,7 @@
 *       DOUBLE PRECISION   D( * ), LLD( * ), W( * ),
 *      $                   WERR( * ), WGAP( * ), WORK( * )
 *       ..
-*  
+*
 *
 *> \par Purpose:
 *  =============
@@ -91,7 +91,7 @@
 *>          RTOL2 is DOUBLE PRECISION
 *>          Tolerance for the convergence of the bisection intervals.
 *>          An interval [LEFT,RIGHT] has converged if
-*>          RIGHT-LEFT.LT.MAX( RTOL1*GAP, RTOL2*MAX(|LEFT|,|RIGHT|) )
+*>          RIGHT-LEFT < MAX( RTOL1*GAP, RTOL2*MAX(|LEFT|,|RIGHT|) )
 *>          where GAP is the (estimated) distance to the nearest
 *>          eigenvalue.
 *> \endverbatim
@@ -107,7 +107,7 @@
 *> \verbatim
 *>          W is DOUBLE PRECISION array, dimension (N)
 *>          On input, W( IFIRST-OFFSET ) through W( ILAST-OFFSET ) are
-*>          estimates of the eigenvalues of L D L^T indexed IFIRST throug
+*>          estimates of the eigenvalues of L D L^T indexed IFIRST through
 *>          ILAST.
 *>          On output, these estimates are refined.
 *> \endverbatim
@@ -117,7 +117,7 @@
 *>          WGAP is DOUBLE PRECISION array, dimension (N-1)
 *>          On input, the (estimated) gaps between consecutive
 *>          eigenvalues of L D L^T, i.e., WGAP(I-OFFSET) is the gap between
-*>          eigenvalues I and I+1. Note that if IFIRST.EQ.ILAST
+*>          eigenvalues I and I+1. Note that if IFIRST = ILAST
 *>          then WGAP(IFIRST-OFFSET) must be set to ZERO.
 *>          On output, these gaps are refined.
 *> \endverbatim
@@ -173,14 +173,12 @@
 *  Authors:
 *  ========
 *
-*> \author Univ. of Tennessee 
-*> \author Univ. of California Berkeley 
-*> \author Univ. of Colorado Denver 
-*> \author NAG Ltd. 
-*
-*> \date November 2011
+*> \author Univ. of Tennessee
+*> \author Univ. of California Berkeley
+*> \author Univ. of Colorado Denver
+*> \author NAG Ltd.
 *
-*> \ingroup auxOTHERauxiliary
+*> \ingroup OTHERauxiliary
 *
 *> \par Contributors:
 *  ==================
@@ -196,10 +194,9 @@
      $                   RTOL2, OFFSET, W, WGAP, WERR, WORK, IWORK,
      $                   PIVMIN, SPDIAM, TWIST, INFO )
 *
-*  -- LAPACK auxiliary routine (version 3.4.0) --
+*  -- LAPACK auxiliary routine --
 *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
-*     November 2011
 *
 *     .. Scalar Arguments ..
       INTEGER            IFIRST, ILAST, INFO, N, OFFSET, TWIST
@@ -237,6 +234,12 @@
 *
       INFO = 0
 *
+*     Quick return if possible
+*
+      IF( N.LE.0 ) THEN
+         RETURN
+      END IF
+*
       MAXITR = INT( ( LOG( SPDIAM+PIVMIN )-LOG( PIVMIN ) ) /
      $           LOG( TWO ) ) + 2
       MNWDTH = TWO * PIVMIN