Bug introduced in version 10.3 or earlier and fixed in 11.1.

I was pleasantly surprised that Mathematica (10.3, 10.4, 10.4.1, 11.0 and 11.0.1) had the unit $\text{flick}$ until I spent several hours trying to figure out why all my calculations were million times off! I think this is a very simple bug. That unless you are dealing with odd spectral radiance units you would never see it.

Mathematica's internal definition for a $\text{flick}$ is wrong.

A $\text{flick}$ is:
$1 \text{flick} = 1\; \frac{\text{W}}{\text{cm}^2\; \text{sr}\; \mu \text{m}}$
Here are some external links for the definition of a $\text{flick}$
Wikipedia (Flick)
A Dictionary of Units of Measurement
Physics Wiki

Set L to be one $\text{flick}$

 L = Quantity[1, "Flicks"]


Lets convert one $\text{flick}$ to one $\frac{\text{W}}{\text{cm}^2\; \text{sr}\; \mu \text{m}}$

  UnitConvert[L, "Watts"/(("Centimeters")^2 "Steradians"  "Micrometers")]
 1 000 000 W/(cm^2 \[Micro]m sr)

Have I missed something simple in how I'm doing the conversion? I'm going to guess that because the $\mu\text{flick}$ is the most common unit of $\text{flick}$ that a $\mu\text{flick}$ accidentally got defined as a $\text{flick}$.

  • $\begingroup$ As a matter of policy, we traditionally do not add the bugs tag until your observations have been verified by others. Nevertheless, running UnitConvert[Quantity[1, "Flicks"]] // N does show that something's off, so this is certainly a bug, and I'll let you off this time. $\endgroup$ – J. M.'s ennui Apr 3 '16 at 22:57
  • $\begingroup$ Sorry I did quick look over the Mathematica meta but must have missed that. $\endgroup$ – c186282 Apr 4 '16 at 0:00
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    $\begingroup$ It's in meta (there are also a number of related questions), and it is also in the tag wiki $\endgroup$ – J. M.'s ennui Apr 4 '16 at 0:03
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    $\begingroup$ @c186282 You should report this to Wolfram Support, if you haven't yet! As you probably know, this forum is not associated with Wolfram, so reporting bugs here does not notify Wolfram. $\endgroup$ – MarcoB Apr 4 '16 at 20:21
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    $\begingroup$ As I said "Yes I have sent a link to this post to my Wolfram contact." well Flicks are still wrong in 11.0 $\endgroup$ – c186282 Aug 13 '16 at 0:43

No bug. You should use "Microns" instead of "Micrometers" in UnitConvert

  • $\begingroup$ “Micrometers” is perfectly fine. I think the bug may have been fixed in version 12 (I could only check The online version). $\endgroup$ – MarcoB May 21 '20 at 2:56
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    $\begingroup$ Yes the bug has been fixed finally. (But I still use my workaround.) Also, "Microns" and "Micrometers" are the same things but I prefer "Micrometers" because it is linguistically consistent with the other length units. $\endgroup$ – c186282 May 24 '20 at 13:54
  • $\begingroup$ See section "SI Standardization" in en.wikipedia.org/wiki/Micrometre. $\endgroup$ – murray Jun 20 '20 at 15:09

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