seq: work around floating point inaccuracies on more systems

* src/seq.c: Include <math.h> for fabs.
Include <float.h> for DBL_EPSILON.
(abs_rel_diff): New function.
(print_numbers): Use abs_rel_diff rather than a strict equality test.
Without this change, Solaris 8 and Irix 6.2 would fail the float-6
test.  Reported by Peter Fales in
http://thread.gmane.org/gmane.comp.gnu.coreutils.bugs/13183
* src/c99-to-c89.diff: Adjust seq.c offsets.

1 files changed, 11 insertions, 1 deletions

diff --git a/src/seq.c b/src/seq.c
index 64bbeee00..7fc89ad5d 100644
--- a/src/seq.c
+++ b/src/seq.c
@@ -20,6 +20,8 @@
 #include <getopt.h>
 #include <stdio.h>
 #include <sys/types.h>
+#include <math.h>
+#include <float.h>
 
 #include "system.h"
 #include "c-strtod.h"
@@ -259,6 +261,14 @@ long_double_format (char const *fmt, struct layout *layout)
   return NULL;
 }
 
+/* Return the absolute relative difference from x to y.  */
+static double
+abs_rel_diff (double x, double y)
+{
+  double s = (y == 0.0 ? 1 : y);
+  return fabs ((y - x) / s);
+}
+
 /* Actually print the sequence of numbers in the specified range, with the
    given or default stepping and format.  */
 
@@ -300,7 +310,7 @@ print_numbers (char const *fmt, struct layout layout,
 	      x_str[x_strlen - layout.suffix_len] = '\0';
 
 	      if (xstrtold (x_str + layout.prefix_len, NULL, &x_val, c_strtold)
-		  && x_val == last)
+		  && abs_rel_diff (x_val, last) < DBL_EPSILON)
 		{
 		  char *x0_str = NULL;
 		  if (asprintf (&x0_str, fmt, x0) < 0)