Re: [9fans] a bug in awk?
hi erik,
i had a temp code in dumvacroots.new:
...
rc |
awk '/5946903e/ { next; }
$3==16 {printf(%s\n, $0)}'
which i removed it now, built awk with your fix in place and tried.
the problem is fixed now.
thanks for the fix.
regards
dharani
On Sat, Jan 10, 2009 at 1:45 PM, erik quanstrom quans...@quanstro.net wrote:
For what it's worth, bwk awk does not have this problem, so the error
must be in code introduced later.
Note the 5946903e318 which AWK may mistakenly treat as a floating
point constant. Now to figure how to prevent such errors...
from the better than nothin' department ...
i have an inelegant couple of lines that prevent overflow.
one would expect that for a postitive exponent that if
nwholedigits + exponent - 1 the maximum exp.
then you'll have an overflow. (ideally one should do this
computation in ieee space, but that's not what the code
does.) i put this simple test in the natural place and
it seems to avoid the floating point exception (tested on intel
machines). the problem seems to be that the code deals
with very small overflows, but isn't prepared to deal with
a number that's going to overflow by a lot. in this case,
we're 1^(10 + 6) too big.
; diffy strtod.c
396a397,398
if(nd0 + e1 - 1 DBL_MAX_10_EXP)
goto ovfl;
431a434,435
if(e1 - (nd-nd0) DBL_MAX_10_EXP)
goto undfl;
is it even legal to return DBL_MAX for numbers that should
be +Inf or DBL_MIN for numbers that should yield -Inf?
is there some reason that the regular strtod is unsuitable for
ape?
- erik
Re: [9fans] a bug in awk?
For what it's worth, bwk awk does not have this problem, so the error must be in code introduced later. Note the 5946903e318 which AWK may mistakenly treat as a floating point constant. Now to figure how to prevent such errors... -- John Stalker School of Mathematics Trinity College Dublin tel +353 1 896 1983 fax +353 1 896 2282
Re: [9fans] a bug in awk?
For what it's worth, bwk awk does not have this problem, so the error must be in code introduced later. Note the 5946903e318 which AWK may mistakenly treat as a floating point constant. Now to figure how to prevent such errors... from the better than nothin' department ... i have an inelegant couple of lines that prevent overflow. one would expect that for a postitive exponent that if nwholedigits + exponent - 1 the maximum exp. then you'll have an overflow. (ideally one should do this computation in ieee space, but that's not what the code does.) i put this simple test in the natural place and it seems to avoid the floating point exception (tested on intel machines). the problem seems to be that the code deals with very small overflows, but isn't prepared to deal with a number that's going to overflow by a lot. in this case, we're 1^(10 + 6) too big. ; diffy strtod.c 396a397,398 if(nd0 + e1 - 1 DBL_MAX_10_EXP) goto ovfl; 431a434,435 if(e1 - (nd-nd0) DBL_MAX_10_EXP) goto undfl; is it even legal to return DBL_MAX for numbers that should be +Inf or DBL_MIN for numbers that should yield -Inf? is there some reason that the regular strtod is unsuitable for ape? - erik
Re: [9fans] a bug in awk?
is there some reason that the regular strtod is unsuitable for ape? for one thing, the regular (= plan 9 libc) strtod doesn't set errno. russ
Re: [9fans] a bug in awk?
is there some reason that the regular strtod is unsuitable for ape? for one thing, the regular (= plan 9 libc) strtod doesn't set errno. i didn't say exactly what i ment. would adding errno setting and potentially altering return values (i'm not clear if this is necessary) be sufficient to use the libc strtod with ape? - erik
Re: [9fans] a bug in awk?
11258672 5946903e318d3596c21e35b42a13c1dea5fd32cc 0 Note the 5946903e318 which AWK may mistakenly treat as a floating point constant. Now to figure how to prevent such errors... ++L
Re: [9fans] a bug in awk?
hi lucio, so, it tries to interpret as a floating-point no and goes for a toss! thanks for the quick response. regards dharani On Fri, Jan 9, 2009 at 10:26 PM, lu...@proxima.alt.za wrote: 11258672 5946903e318d3596c21e35b42a13c1dea5fd32cc 0 Note the 5946903e318 which AWK may mistakenly treat as a floating point constant. Now to figure how to prevent such errors... ++L
