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* src/seq.c (print_numbers): Rewrite in an attempt to avoid the

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more-general rounding issues exposed by the previous patch.
This commit is contained in:
Paul Eggert
2007-11-21 18:37:08 +01:00
committed by Jim Meyering
parent a9805326e4
commit 32f31bad5e
2 changed files with 30 additions and 31 deletions
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5
ChangeLog
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@@ -1,3 +1,8 @@
2007-11-18 Paul Eggert <eggert@cs.ucla.edu>
* src/seq.c (print_numbers): Rewrite in an attempt to avoid the
more-general rounding issues exposed by the previous patch.
2007-11-18 Jim Meyering <meyering@redhat.com>
* src/c99-to-c89.diff: Adjust seq.c offsets.

56
src/seq.c
View File

@@ -238,24 +238,32 @@ static void
print_numbers (char const *fmt, struct layout layout,
long double first, long double step, long double last)
{
long double i;
long double x0 IF_LINT (= 0);
bool out_of_range = (step < 0 ? first < last : last < first);
for (i = 0; /* empty */; i++)
if (! out_of_range)
{
long double x = first + i * step;
long double x = first;
long double i;
if (step < 0 ? x < last : last < x)
for (i = 1; ; i++)
{
/* If we go one past the end, but that number prints as a
value equal to "last", and prints differently from the
previous number, then print "last". This avoids problems
with rounding. For example, with the x86 it causes "seq
0 0.000001 0.000003" to print 0.000003 instead of
stopping at 0.000002. */
long double x0 = x;
printf (fmt, x);
if (out_of_range)
break;
x = first + i * step;
out_of_range = (step < 0 ? x < last : last < x);
if (i)
if (out_of_range)
{
/* If the number just past LAST prints as a value equal
to LAST, and prints differently from the previous
number, then print the number. This avoids problems
with rounding. For example, with the x86 it causes
"seq 0 0.000001 0.000003" to print 0.000003 instead
of stopping at 0.000002. */
bool print_extra_number = false;
long double x_val;
char *x_str;
int x_strlen = asprintf (&x_str, fmt, x);
@@ -269,34 +277,20 @@ print_numbers (char const *fmt, struct layout layout,
char *x0_str = NULL;
if (asprintf (&x0_str, fmt, x0) < 0)
xalloc_die ();
if (!STREQ (x0_str, x_str))
{
fputs (separator, stdout);
fputs (x_str, stdout);
}
print_extra_number = !STREQ (x0_str, x_str);
free (x0_str);
}
free (x_str);
if (! print_extra_number)
break;
}
/* With floating point arithmetic, we may well reach this point
with i == 0 and first == last. E.g., ./seq .1 .1 on FreeBSD 6.1.
Hence the first conjunct: don't break out of this loop when
i == 0. *unless* first and last themselves are out of order,
in which case we must print nothing, e.g. for ./seq -1 */
if (i || (0 < step && last < first) || (step < 0 && first < last))
break;
fputs (separator, stdout);
}
if (i)
fputs (separator, stdout);
printf (fmt, x);
x0 = x;
fputs (terminator, stdout);
}
if (i)
fputs (terminator, stdout);
}
/* Return the default format given FIRST, STEP, and LAST. */