--- rpl/lapack/lapack/dlarrv.f 2016/08/27 15:27:10 1.17
+++ rpl/lapack/lapack/dlarrv.f 2023/08/07 08:38:58 1.24
@@ -2,18 +2,18 @@
*
* =========== 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 DLARRV + dependencies
-*>
-*> [TGZ]
-*>
-*> [ZIP]
-*>
+*> Download DLARRV + dependencies
+*>
+*> [TGZ]
+*>
+*> [ZIP]
+*>
*> [TXT]
-*> \endhtmlonly
+*> \endhtmlonly
*
* Definition:
* ===========
@@ -23,7 +23,7 @@
* RTOL1, RTOL2, W, WERR, WGAP,
* IBLOCK, INDEXW, GERS, Z, LDZ, ISUPPZ,
* WORK, IWORK, INFO )
-*
+*
* .. Scalar Arguments ..
* INTEGER DOL, DOU, INFO, LDZ, M, N
* DOUBLE PRECISION MINRGP, PIVMIN, RTOL1, RTOL2, VL, VU
@@ -35,7 +35,7 @@
* $ WGAP( * ), WORK( * )
* DOUBLE PRECISION Z( LDZ, * )
* ..
-*
+*
*
*> \par Purpose:
* =============
@@ -68,8 +68,14 @@
*> \verbatim
*> VU is DOUBLE PRECISION
*> Upper bound of the interval that contains the desired
-*> eigenvalues. VL < VU. Needed to compute gaps on the left or right
-*> end of the extremal eigenvalues in the desired RANGE.
+*> eigenvalues. VL < VU.
+*> Note: VU is currently not used by this implementation of DLARRV, VU is
+*> passed to DLARRV because it could be used compute gaps on the right end
+*> of the extremal eigenvalues. However, with not much initial accuracy in
+*> LAMBDA and VU, the formula can lead to an overestimation of the right gap
+*> and thus to inadequately early RQI 'convergence'. This is currently
+*> prevented this by forcing a small right gap. And so it turns out that VU
+*> is currently not used by this implementation of DLARRV.
*> \endverbatim
*>
*> \param[in,out] D
@@ -143,7 +149,7 @@
*> RTOL2 is DOUBLE PRECISION
*> Parameters for bisection.
*> 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|) )
*> \endverbatim
*>
*> \param[in,out] W
@@ -261,12 +267,10 @@
* Authors:
* ========
*
-*> \author Univ. of Tennessee
-*> \author Univ. of California Berkeley
-*> \author Univ. of Colorado Denver
-*> \author NAG Ltd.
-*
-*> \date June 2016
+*> \author Univ. of Tennessee
+*> \author Univ. of California Berkeley
+*> \author Univ. of Colorado Denver
+*> \author NAG Ltd.
*
*> \ingroup doubleOTHERauxiliary
*
@@ -286,10 +290,9 @@
$ IBLOCK, INDEXW, GERS, Z, LDZ, ISUPPZ,
$ WORK, IWORK, INFO )
*
-* -- LAPACK auxiliary routine (version 3.6.1) --
+* -- LAPACK auxiliary routine --
* -- LAPACK is a software package provided by Univ. of Tennessee, --
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
-* June 2016
*
* .. Scalar Arguments ..
INTEGER DOL, DOU, INFO, LDZ, M, N
@@ -344,6 +347,13 @@
* ..
INFO = 0
+*
+* Quick return if possible
+*
+ IF( (N.LE.0).OR.(M.LE.0) ) THEN
+ RETURN
+ END IF
+*
* The first N entries of WORK are reserved for the eigenvalues
INDLD = N+1
INDLLD= 2*N+1