Bug introduced in 10.0 and fixed in 10.0.2

I want to format numbers in decimal notation and chose TextString for this task. But today, when looking at the final result of my 3-weeks measurement, the sign seemed odd. I traced it to the following, unexpected behaviour of TextString:

(*  1.0  *)

(* -1.0  *)

(* 0.5  UNEXPECTED *)

Using Trace gave a huge string of output that I am unable to interpret. Is TextString the wrong tool for this job?

  • 7
    $\begingroup$ Looks like a nasty bug, adding tag. Please report it to WRI, and do mention your measurements and the consequences. $\endgroup$
    – Szabolcs
    Nov 13, 2014 at 15:18

2 Answers 2


Not much to say here other than this is a nasty bug, but since you seemed to be curious what exactly goes wrong, here's the function that does the formatting:

Mathematica graphics

This function breaks the number into integer and fractional parts, converts both to a string (as integers) and joins them with a decimal point. The integer part of -0.5 is 0 which is formatted as 0, not as -0.

  • $\begingroup$ How exactly did you find this? All I could find is i.stack.imgur.com/1aHe9.png which is pretty horrible. $\endgroup$
    – Öskå
    Nov 13, 2014 at 15:31
  • $\begingroup$ @Öskå Check this out: mathematica.stackexchange.com/a/15948/12 (get the github version of the code) $\endgroup$
    – Szabolcs
    Nov 13, 2014 at 15:32
  • 15
    $\begingroup$ @Mr.Wizard No, won't fix it. I'm really annoyed by the recent decline in quality . When one has spare time, it might be fun digging up problems like this. But when it affects our work directly, and wastes a lot of time, then it is horrible. I can imagine that after an experience like Martin's (messing up his experimental results and wasting a lot of time) many people wouldn't touch Mma with a 10 foot pole. It can't even format a number reliably! $\endgroup$
    – Szabolcs
    Nov 13, 2014 at 15:44
  • 8
    $\begingroup$ @Szabolcs this will be fixed in 10.0.2. Very unfortunate bug, I apologize! Personally, most developers and testers I know wanted more time to iron out kinks like these, but we do not set the cadence of our release cycle. $\endgroup$ Nov 19, 2014 at 23:16
  • 1
    $\begingroup$ @Taliesin Is there any constructive channel in which we might support the position of "most developers and testers"? Will anyone listen? $\endgroup$
    – Mr.Wizard
    Aug 2, 2015 at 2:33

This has been fixed in Version 10.0.2. On windows:


Mathematica graphics


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