This is really old school, but a lot of times we have users sending us
copy pasting of codes, and that is the only way to know the version of
the code.
This is mostly a long term maintenance improvement.
Many coding styles require elimination of trailing whitespace, and
many editors and source code management configurations automatically
gobble up whitespace. When these tools gobble up whitespace, it
complicates reviewing the meaningful code changes.
By removing whitespace on one patch, it makes future
code reviews much easier.
=SCRIPT====================================================================
if which tempfile &>/dev/null; then
TEMPMAKER=tempfile
elif which mktemp &>/dev/null; then
TEMPMAKER=mktemp
else
echo "Cannot find tempfile program." 2>&1
exit 1
fi
MYTEMP=$($TEMPMAKER)
trap 'rm -f $MYTEMP' SIGINT SIGTERM
stripit() {
echo "stripping $1"
sed 's/[ \t]*$//' "$1" > $MYTEMP
cp $MYTEMP "$1"
}
if [ $# -gt 0 ]; then
while [ "$1" != "" ]; do
stripit $1
shift
done
else
while read -t 2; do
stripit $REPLY
done
fi
rm $MYTEMP
=================================================
Description of bug http://icl.utk.edu/lapack-forum/viewtopic.php?f=13&t=4391,
It turns out to be related to bug http://icl.cs.utk.edu/lapack-forum/viewtopic.php?f=5&t=4498 as well. Further, I suspect that the problem reported in an e-mail sent by Justin Weiguang Si to lapack@cs.utk.edu on Sep 22 is also related to those, although Justin has not yet replied to my request for the offending matrix...
The bug has been traced to [d/s]laed6, which computes the root closest to the origin of a secular equation and is used in the D&C tridiagonal eigensolver (DSTEDC) and D&C least squares solver (DGELSD). We have interacted with Ren-Cang Li (the original developer of [d/s]laed6) about possible fixes, and I am attaching a new version of [d/s]laed6. This version has been tested with our 'torture cases' (more on this below) in:
- single and double precision
- Intel Xeon Westmere with gnu (gfortran) and intel (ifort) compilers
- AMD MagnyCours with pgi, cray, intel and gnu compilers
The bug was related to a too stringent tolerance convergence criterion, line 390 in laed6. The fix is
390 IF( ( ABS( F ).LE.FOUR*EPS*ERRETM ) .OR.
391 $ ( (UBD-LBD).LE.FOUR*EPS*ABS(TAU) ) )
to replace
390 IF( ABS( F ).LE.EPS*ERRETM )
corrected bugs: 115 and 121
Got a new bug for you! Mick Pont found this problem in DLAED6. The code in question is the 40 loop - when DSCALE(I)=TAU you get a divide by zero (rare in practice). This can cause some compilers to immediately stop, e.g. the Sun compiler.
Mick proposed solution is below:
DO 40 I = 1, 3
IF (DSCALE( I ).NE.TAU) THEN
TEMP = ONE / ( DSCALE( I )-TAU )
TEMP1 = ZSCALE( I )*TEMP
TEMP2 = TEMP1*TEMP
TEMP3 = TEMP2*TEMP
TEMP4 = TEMP1 / DSCALE( I )
FC = FC + TEMP4
ERRETM = ERRETM + ABS( TEMP4 )
DF = DF + TEMP2
DDF = DDF + TEMP3
ELSE
* On rare occasions dscale(i) can be exactly equal to
* tau, leading to division by zero. If no trap occurs,
* there is no problem; the quantities above all overflow
* and the test on abs(f) below sends you to the end
* with good results. If a trap occurs, though, the
* user program will stop. Avoid that happening by
* jumping directly out.
GO TO 60
END IF
40 CONTINUE
This seems to work OK in our testing.
Use \par instead of \details for section.
add a Contributors Section and a Reference Section.
Remove (some) verbatim section when not needed.
Those changes have been done by hand so I am not sure I manage to catch them all.
Mark Gates