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author | Julien Langou <julien.langou@ucdenver.edu> | 2017-04-13 09:04:48 (GMT) |
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committer | Julien Langou <julien.langou@ucdenver.edu> | 2017-04-13 09:04:48 (GMT) |

commit | 60d5dbc65d5aae00b82176511aabbf6be4f45d17 (patch) | |

tree | 1b9653986709be75f49b11e16ff7ec01f0c4d2fc | |

parent | 4445018037d3d3de71ecbadfbd0c0196532ad4c1 (diff) | |

download | lapack-60d5dbc65d5aae00b82176511aabbf6be4f45d17.zip lapack-60d5dbc65d5aae00b82176511aabbf6be4f45d17.tar.gz lapack-60d5dbc65d5aae00b82176511aabbf6be4f45d17.tar.bz2 |

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.

-rw-r--r-- | SRC/dlarrv.f | 10 | ||||

-rw-r--r-- | SRC/slarrv.f | 10 |

2 files changed, 16 insertions, 4 deletions

diff --git a/SRC/dlarrv.f b/SRC/dlarrv.f index 8006a75..4e8d204 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 73bebb3..675aac3 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 |