# How to write uncertainties with the \pm symbol "10 ± 1 K" by using siunitx?

Using the siunitx package, if I specify an error with the \pm symbol then it automatically converts it to a form using parenthesis. I would like it to not do this and keep the \pm symbol, but still space the elements of the quantity and symbol in a good way.

e.g. \SI{10 \pm 2}{\kelvin} would produce 10(1) K

I would like it to produce: 10\pm1 K or something similar with spacing taken care of.

You want the separate-uncertainty switch, p.30 of the documentation.

\usepackage[separate-uncertainty=true]{siunitx}


sets this format for every number, or

\SI[separate-uncertainty=true]{whatever}


just for one.

• Ant, you're a star, just the correct option. I'm surprised I didn't find it myself as I thought I did a search for "uncertainty" in the manual. No matter. Thanks very much Sep 6 '11 at 21:45
• I'd note that \sisetup{separate-uncertainty=true} is also an option, which can be called in your document before you need the format change. Dec 2 '19 at 11:46

I've just come across the same problem and this is how I solved it to my satisfaction:

in the preamble:

\usepackage[separate-uncertainty = true,multi-part-units=single]{siunitx}


in the text:

(\SI{284(10)}{\ampere})


Produces the following output: 284 ± 10 A

If multi-part-units=single option isn't given, the result will look like: ((284 ± 10) A) which, in my opinion, is less than optimal.

HTH

• Hmm, it even seemed multi-part-units=single was sufficient for me. You don't need the first part to achieve the same result... but that's 5 years later. Mar 3 '18 at 18:28
• I needed the first part as of 06/2019. Jun 17 '19 at 23:13