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RE: LAPACK results for cygwin - one problem
- To: "'gcc-bugs at gcc dot gnu dot org'" <gcc-bugs at gcc dot gnu dot org>
- Subject: RE: LAPACK results for cygwin - one problem
- From: "Billinghurst, David (CRTS)" <David dot Billinghurst at riotinto dot com>
- Date: Fri, 25 May 2001 02:16:55 -0000
- Cc: "'schmid at snake dot iap dot physik dot tu-darmstadt dot de'" <schmid at snake dot iap dot physik dot tu-darmstadt dot de>
I have investigated this failure of the LAPACK tests of CGV drivers in cgd
on i686-pc-cygwin. I believe the errors are due to small rounding
differences or additional precision in floating point operations.
The failures depend on the optimisation level on file chgeqz.f, independent
of the optimisation used on the rest of LAPACK, and start at -O2
I then isolated and analysed a failure on a 2x2 matrix. For this case the
failure is due to a change of order 1.0e-16 in a quantity of order 1.0e-8,
at the level of round off for single precision floating point.
It is known that Givens rotations, used in this routine, can be sensitive to
pertubation. See LAPACK working notes 148 (On Computing Givens rotations
reliably and efficiently) and 150 (Discontinuous Plane Rotations and the
Symmetric Eigenvalue Problem) available from
http://www.netlib.org/lapack/lawns/index.html
I may look into this some more, but I believe this is not a g77 regression.
> -----Original Message-----
> From: Billinghurst, David (CRTS)
> Sent: Wednesday, 23 May 2001 14:34
> To: 'gcc-bugs@gcc.gnu.org'
> Cc: 'schmid@snake.iap.physik.tu-darmstadt.de'
> Subject: LAPACK results for cygwin - one problem
>
> Here are some i686-pc-cygwin LAPACK results for the branch. Couldn't
> decide
> which flags to use, so ...
>
> These results are similar to i686-pc-gnu-linux results from Peter Schmid,
> http://gcc.gnu.org/ml/gcc/2001-05/msg00625.html. The [CZ]GV driver fails
> are a regression from 2.95. Otherwise OK. I should be able to generate
> a
> test case, but it may take a couple of evenings.
>
> -O3 -funroll-loops
>
> cgd.out: CGV drivers: 66 out of 1092 tests failed to pass the
> threshold
> csvd.out: CBD: 1 out of 4085 tests failed to pass the threshold
> dgd.out: DXV drivers: 200 out of 5000 tests failed to pass the
> threshold
> sgd.out: SXV drivers: 37 out of 5000 tests failed to pass the
> threshold
> ssep.out: SST drivers: 1 out of 14256 tests failed to pass the
> threshold
> zgd.out: ZGV drivers: 61 out of 1092 tests failed to pass the
> threshold
> zgd.out: ZXV drivers: 24 out of 5000 tests failed to pass the
> threshold
>
>
> -O0 -ffloat-store
>
> csep.out: CST: 1 out of 4662 tests failed to pass the threshold
> csep.out: CST drivers: 1 out of 11664 tests failed to pass the
> threshold
> csep.out: CST: 1 out of 4662 tests failed to pass the threshold
> ded.out: DES: 1 out of 3270 tests failed to pass the threshold
> ded.out: DSX: 1 out of 3500 tests failed to pass the threshold
> dgd.out: DXV drivers: 200 out of 5000 tests failed to pass the
> threshold
> sgd.out: SXV drivers: 37 out of 5000 tests failed to pass the
> threshold
> ssep.out: SST: 1 out of 4662 tests failed to pass the threshold
> ssep.out: SST: 2 out of 4662 tests failed to pass the threshold
> ssep.out: SST drivers: 1 out of 14256 tests failed to pass the
> threshold
> ssvd.out: SBD: 1 out of 5510 tests failed to pass the threshold
> zgd.out: ZXV drivers: 24 out of 5000 tests failed to pass the
> threshold
>
>
> -O1
>
> csep.out: CST: 1 out of 4662 tests failed to pass the threshold
> csep.out: CST drivers: 1 out of 11664 tests failed to pass the
> threshold
> csvd.out: CBD: 1 out of 4085 tests failed to pass the threshold
> csvd.out: CBD: 1 out of 4085 tests failed to pass the threshold
> dgd.out: DXV drivers: 200 out of 5000 tests failed to pass the
> threshold
> sgd.out: SXV drivers: 37 out of 5000 tests failed to pass the
> threshold
> ssep.out: SST drivers: 1 out of 14256 tests failed to pass the
> threshold
> zgd.out: ZXV drivers: 24 out of 5000 tests failed to pass the
> threshold
>
>
> -O2
>
> cgd.out: CGV drivers: 66 out of 1092 tests failed to pass the
> threshold
> csvd.out: CBD: 1 out of 4085 tests failed to pass the threshold
> dgd.out: DXV drivers: 200 out of 5000 tests failed to pass the
> threshold
> sgd.out: SXV drivers: 37 out of 5000 tests failed to pass the
> threshold
> ssep.out: SST drivers: 1 out of 14256 tests failed to pass the
> threshold
> zgd.out: ZGV drivers: 61 out of 1092 tests failed to pass the
> threshold
> zgd.out: ZXV drivers: 24 out of 5000 tests failed to pass the
> threshold
>
>
> -Os
>
> csep.out: CST: 1 out of 4662 tests failed to pass the threshold
> csep.out: CST drivers: 1 out of 11664 tests failed to pass the
> threshold
> csvd.out: CBD: 1 out of 4085 tests failed to pass the threshold
> csvd.out: CBD: 1 out of 4085 tests failed to pass the threshold
> dgd.out: DXV drivers: 200 out of 5000 tests failed to pass the
> threshold
> dnep.out: DHS: 1 out of 1764 tests failed to pass the threshold
> sgd.out: SXV drivers: 37 out of 5000 tests failed to pass the
> threshold
> ssep.out: SST drivers: 1 out of 14256 tests failed to pass the
> threshold
> zgd.out: ZXV drivers: 24 out of 5000 tests failed to pass the
> threshold
>
> +++++++++++++++++++++++++++++++++++++++++
> (Mr) David Billinghurst
> Comalco Research Centre
> PO Box 316, Thomastown, Vic, Australia, 3074
> Phone: +61 3 9469 0642
> FAX: +61 3 9462 2700
> Email: David.Billinghurst@riotinto.com
>
>