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Re: slowness of Schur decomposition in octave-2

From: Takafumi Hayashi
Subject: Re: slowness of Schur decomposition in octave-2
Date: Mon, 07 Jul 1997 23:15:17 +0900

>  If the reference time was produced with an Octave version build with
>  G77, it would explain the bad result for the Schur decomposition. A
>  few months ago i have tested the OS/2 version of the G77 and the most
>  significant change was, that the Schur decomposition was 43 % slower
>  (compared to the value for the Octave build with f2c). This was
>  because the G77 uses static variables, while the f2c was configured
>  to automatic variables. I've tried to change this, but when G77 also
>  uses automatic variables, Octave crashes sometimes and on the other
>  hand Octave is not faster than the with f2c compiled version.  So i
>  decided to uses f2c.
I forwarded this message to g77 list.
I got comments...

This sounds like some sort of OS/2 lossage to me.  Octave on my x86
GNU/Linux system doesn't try to compile anything with -fno-automatic
AFAICT and it passed all the tests (when I hacked configure
appropriately).  I no longer have a compiled version to run, though.

address@hidden octave]$ find . -name Make\* |xargs grep no-automatic
address@hidden octave]$

Of course, if it did use -fno-automatic and g77 0.5.18, the slowness
is understandable.
Takafumi Hayashi             address@hidden
The University of Aizu       phone : +81-242-37-2614
FCS Lab.                     fax   : +81-242-37-2734

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