seq: numerical precision issue causing difference from GNU output

[jfinkels]

This was found by the fuzzer in this job https://github.com/uutils/coreutils/actions/runs/12875524963/job/35897027858?pr=7181#step:7:4790. The logs for this test case started with

Running test ["seq", "18.499885215552325", "-0.0918587338370287", "-5068"]
Test Type: seq
Input: ["18.499885215552325", "-0.0918587338370287", "-5068"]
Rust stdout: 18.4998852155523250
# very long output...

You can narrow the test case down a bit to just

$ seq 18.499885215552325 -0.0918587338370287 -1006.7 |tail

Here is the diff between the output of GNU seq and that of uutils seq:

--- gnu	2025-01-20 16:20:55.686430468 -0500
+++ uutils	2025-01-20 16:20:58.638351255 -0500
@@ -2,9 +2,9 @@
 -1005.9087145349917374
 -1006.0005732688287661
 -1006.0924320026657948
--1006.1842907365028236
--1006.2761494703398523
--1006.3680082041768810
--1006.4598669380139097
+-1006.1842907365028235
+-1006.2761494703398522
+-1006.3680082041768809
+-1006.4598669380139096
 -1006.5517256718509383
 -1006.6435844056879670

There is a very small difference between some of the numbers due to some numerical precision issue. (The difference is in the last digit.)

[jfinkels]

Duplicate of #5759 maybe?

[drinkcat]

Yeah, looks the same. And again, output of uutils is the same as coreutils on arm64...