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I'm using siunitx to describe some chemical purities. The purity I would like to describe is sold by the chemical company as 99.9+ % (not the best way of describing it I'm sure). When I try to describe this using siunitx it halts pdflatex.


Is there a way around this problem with siunitx?

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I don't get errors with \SI[parse-numbers=false]{99.9+}{\percent}, but it doesn't seem a mathematically correct way of writing this: why not at least \SI{99.9}{\percent}? – egreg Jan 18 '12 at 23:51
@egreg: That may be delving into political chemistry... of course, something we're removed from. – Werner Jan 19 '12 at 0:08
Instead of the unusual 99.9+ % notation, you could say \SI{>=99.9}{\percent}, which will give you the properly formatted and more mathematically correct output ≥99.9 %. But if you need to reproduce exactly what the manufacturer told you, egreg's suggestion of switching off the number parser is probably the way to go. – Jake Jan 19 '12 at 2:05
I (used to) work with noble gases. Some of these have a purity of 99.998% or 99.999%. This is a bit messy so a gas purity shorthand developed: 5.0 =99.999% and 4.8=99.998% ie 5 nines and and 4 nines and an eight. I have only seen it used with gases...Is there a 4.9? Does this equal 5.0???!!! – Leeser Jan 19 '12 at 14:15
Thanks for the help guys. Unfortunately the people at the chemical company state the purity as 99.9+%. As much as it hurts my eyes I need to state it as it is on the bottle. @egreg If you make that into an answer I'll accept it. Thanks. – Darling Jan 20 '12 at 0:20
up vote 5 down vote accepted

The option to use is parse-numbers=false. However there are perhaps slightly better ways to render the symbol (or less bad):




enter image description here

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Another possibility would be to add the sign to the list of allowed symbols:

% egreg's nicer versions:






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