From 60d5dbc65d5aae00b82176511aabbf6be4f45d17 Mon Sep 17 00:00:00 2001 From: Julien Langou Date: Thu, 13 Apr 2017 11:04:48 +0200 Subject: Fix #52 Added in comment of xLARRV Note: VU is currently not used by this implmentation 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. --- SRC/dlarrv.f | 10 ++++++++-- SRC/slarrv.f | 10 ++++++++-- 2 files changed, 16 insertions(+), 4 deletions(-) diff --git a/SRC/dlarrv.f b/SRC/dlarrv.f index 8006a75c..4e8d204b 100644 --- a/SRC/dlarrv.f +++ b/SRC/dlarrv.f @@ -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 implmentation 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 diff --git a/SRC/slarrv.f b/SRC/slarrv.f index 73bebb34..675aac3d 100644 --- a/SRC/slarrv.f +++ b/SRC/slarrv.f @@ -68,8 +68,14 @@ *> \verbatim *> VU is REAL *> 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 implmentation of SLARRV, VU is +*> passed to SLARRV 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 SLARRV. *> \endverbatim *> *> \param[in,out] D -- cgit v1.2.3